The Portuguese had fired the hosts into a fourth-minute lead with a tidy finish, but Juventus were level midway through the opening period when Fernando Llorente bundled home from close range.[break]
Ronaldo took his tally to an incredible seven goals in just three Champions League games this season with a penalty five minutes later and Juve´s task became even tougher when Giorgio Chiellini was sent-off just after the interval.
Gareth Bale was then introduced to make his home European debut for Real, but despite failing to make the most of their numerical advantage they held on to make it three wins from three in Group B.
Defeat, however, leaves the Italian champions in a perilous situation with just two points from three games, now two behind Galatasaray after they beat FC Copenhagen 3-1 in the other game in the group on Wednesday.
"After the sending-off they backed off and it was more difficult for us to create opportunities," Madrid captain Iker Casillas told Canal Plus.
"But we have taken an important step towards qualifying with nine points in three games."
The return of Casillas in goal was one of four changes that Real boss Carlo Ancelotti made to his side from the 2-0 win over Malaga at the weekend, but the Spanish captain showed no signs of rustiness as he parried away a fine drive by Claudio Marchisio inside the first two minutes.
Two minutes later and Madrid were in front as Angel Di Maria cut inside and slipped a perfect reverse ball in behind for Ronaldo to round Gianluigi Buffon and find the net from a narrow angle.
Juventus responded brilliantly to going behind, though, as they swarmed forward and Carlos Tevez saw two efforts from distance fly just off target.
And they were deservedly level on 22 minutes when Casillas parried Paul Pogba´s header at the end of a flowing move and Llorente swept home the rebound for just his second Juve goal since joining from Athletic Bilbao.
It took Madrid just seven minutes to edge back in front as referee Manuel Graefe rightly awarded a penalty when Chiellini hauled down Sergio Ramos as the defender tried to get on the end of Di Maria´s free-kick.
Ronaldo stepped up and dispatched the spot-kick with an unerring ease high into the net.
Both sides could have added to their tally before the break as the game rushed from end to end with Andrea Pirlo and Ronaldo firing just off target.
However, the game swung even further in Madrid´s favour just three minutes into the second half when Chiellini was harshly shown a straight red card for bringing down Ronaldo just outside the area.
Karim Benzema should then have sealed the three points when he somehow conspired to fire wide of an open goal from two yards out after great work from Di Maria and Alvaro Arbeloa.
Bale was introduced for the much maligned Benzema with just under 25 minutes remaining, but the Welshman struggled to make any impact on the game and certainly didn´t enhance his chances of starting when Real travel to face Barcelona in La Liga on Saturday.
Narrow win keeps Man United in control
MANCHESTER, United Kingdom, Oct 23: Manchester United ground out a tight 1-0 win over Real Sociedad at Old Trafford on Wednesday to move closer to a place in the Champions League knockout phase.
The decisive goal in the first ever meeting between the teams came within moments of kick-off, Inigo Martinez scoring an own goal after the excellent Wayne Rooney had struck the post.[break]
Both sides hit the woodwork thereafter, Real Sociedad on two occasions, but unlike in Saturday´s 1-1 draw at home to Southampton in the Premier League, United were spared the pain of shipping a late equaliser.
"I thought we played well tonight. I thought we created opportunities," said United manager David Moyes.
"But while it was 1-0, I still had feelings of Saturday left inside me and while it was 1-0, you know you can always lose a goal from a corner kick or a free-kick.
"But it wouldn´t have been right if we hadn´t taken all three points tonight."
Victory, coupled with Bayer Leverkusen´s success against Shakhtar Donetsk, leaves United a point above the German side at the top of Group A ahead of their return fixture against La Real on November 5.
"It makes life difficult when you go 1-0 down so early on," said visiting coach Jagoba Arrasate, whose side have lost their first three games.
"You have to say it´s a fair result."
Amid domestic shortcomings, the win also eased some of the pressure on Moyes, whose storied predecessor, Alex Ferguson, was once again in attendance, a day after launching his new autobiography.
With Robin van Persie carrying minor toe and groin injuries, Javier Hernandez was handed a start up front for United, while La Real recalled captain Xabi Prieto following a spell out with hamstring trouble.
United were trialling a new ´singing section´ in the East Stand and the 1,500 fans in that area were given something to sing about within only 69 seconds of kick-off.
Rooney left three defenders in his wake with an uncharacteristic jinking run on the left-hand edge of the penalty area and although his shot hit the post, Martinez inadvertently shanked the rebound into his own net.
Rooney was one of several players criticised in Ferguson´s book, with the Scot repeating his allegation -- contested by Rooney -- that the striker asked to leave the club in May, but he was at the heart of every United attack.
He had a volley saved by Claudio Bravo and then volleyed acrobatically over the bar from an Antonio Valencia cross, while Hernandez saw a header disallowed for offside.
The visitors began to threaten on the break, however, and after David de Gea tipped a Haris Seferovic shot over, Antoine Griezmann almost silenced the stadium with a free-kick that bounced back off the left-hand upright.
The scares continued early in the second half, with Jonny Evans slicing a cross from Seferovic inches over his own bar in the 51st minute.
Bravo had to produce a sharp save to block a Phil Jones header from point-blank range, but in response, Alberto de la Bella almost embarrassed De Gea with a cross-shot from close to the left-hand touchline that hit the near post.
Rafael ceded his place to Chris Smalling with half an hour to play, apparently due to injury, but gradually United began to reassert control.
Valencia and Rooney each shot straight at Bravo, before the latter produced a piercing through ball for the former, whose low effort came back off the foot of the left-hand post.
Only a smart block by Carlos Martinez prevented Shinji Kagawa from tucking away a pull-back from Valencia, before Rooney blazed a half-volley over from just inside the box.
Substitute Ruben Pardo served a reminder of the visitors´ threat by bending a free-kick a couple of feet wide.
Bravo had to field a curler from Rooney and then rush out to thwart substitute Ashley Young, but although United could not put the game to bed, on this occasion they did not pay the price.
Bayern, PSG the biggest winners on good night for giants
PARIS, Oct 23: Holders Bayern Munich and Paris Saint-Germain were the biggest winners in the Champions League on Wednesday as Real Madrid and both Manchester clubs also recorded important victories.
Frenchman Franck Ribery scored a brace, including one from the penalty spot, while David Alaba, Bastian Schweinsteiger and Mario Goetze were also on target as Pep Guardiola´s Bayern romped to a 5-0 home win against Czech champions Viktoria Pilsen, their eighth consecutive win in the competition.
The German outfit are three points clear at the top of Group D from Manchester City, the Premier League club who claimed a potentially crucial 2-1 win at CSKA Moscow earlier in the day.
City had fallen behind on a difficult pitch at the Arena Khimki when Zoran Tosic lobbed Joe Hart, but Sergio Aguero netted twice before the interval to turn the game on its head.
"It is an important win," City manager Manuel Pellegrini said after the game. "Now we have to play the next two games at home. I told the players that we had to make sure we didn´t lose this one. We are not in the next round yet but this was an important step."
That game was also marred by reports of racist chanting from the home sections of the stadium directed towards City´s Ivorian midfielder Yaya Toure.
"It is unbelievable and very, very sad. We want to stop that and UEFA have to be strong, maybe close the stadium," Toure said.
PSG recorded their biggest European away win as they took Anderlecht apart in Brussels, Zlatan Ibrahimovic scoring four times and Edinson Cavani once in a 5-0 victory.
Ibrahimovic´s evening featured a hat-trick in the space of 19 first-half minutes, with his third goal a ferocious volley from 30 yards that brought many of the home supporters to their feet. And he now has nine goals in his last four games in all competitions.
"Scoring four goals in a game doesn´t happen every day," said Ibrahimovic, who was touched at seeing the Anderlecht fans applaud his marvellous third goal.
"It was incredible, fantastic. I had goose pimples. It is a great honour."
With Oscar Cardozo´s late equaliser earning Benfica a 1-1 draw at home against Olympiakos in Group C´s other, rain-hit, game, PSG are now five points clear at the top and in a position to clinch qualification when they meet Anderlecht at home next.
Despite Ibrahimovic´s feats, the competition´s top scorer is Cristiano Ronaldo, who took his tally for the season to seven with a brace in Real Madrid´s 2-1 win against Juventus at the Santiago Bernabeu.
Ronaldo opened the scoring in the fourth minute and then scored what proved to be the winner just before the half-hour mark following an equaliser by Juve´s Spain striker Fernando Llorente.
Juve could not get back into the game after Giorgio Chiellini was sent off early in the second half, although Madrid captain Iker Casillas said the hosts struggled against the 10 men.
"After the sending-off they backed off and it was more difficult for us to create opportunities," Casillas declared.
"But we have taken an important step towards qualifying with nine points in three games."
Carlo Ancelotti´s side top Group B, while Juve are still without a win and lose second place to Galatasaray, for whom Felipe Melo, Wesley Sneijder and Didier Drogba all scored in a 3-1 victory over FC Copenhagen.
Meanwhile, Manchester United remain in control of Group A, if only just, after a second-minute own-goal by Inigo Martinez gave them a 1-0 home win against Real Sociedad at Old Trafford.
"I thought we played well tonight. I thought we created opportunities," said United manager David Moyes.
"It wouldn´t have been right if we hadn´t taken all three points tonight."
United are a point clear of Bayer Leverkusen, who leapfrogged Shakhtar Donetsk into second place by beating the Ukrainians 4-0 in Germany.
Stefan Kiessling made headlines at the weekend with his now infamous ´phantom goal´ in the Bundesliga, and here he scored twice, either side of a Simon Rolfes penalty and Sidney Sam´s effort to give Sami Hyypia´s men a fine victory.
Brilliant Ibrahimovic tears apart Anderlecht
BRUSSELS, Oct 23: A sensational performance by Zlatan Ibrahimovic helped Paris Saint-Germain continue their perfect start in Champions League Group C with a 5-0 win at Anderlecht on Wednesday.
Sweden star Ibrahimovic scored a hat-trick in the space of 19 first-half minutes at the Stade Constant Vanden Stock in Brussels, one of the quickest triples in the competition´s history.
He netted another in the 62nd minute, after Edinson Cavani had also found the target after the break, as PSG made it three convincing wins from three group games to close in on a last-16 berth.
Ibrahimovic now has nine goals from his last four games in all competitions, while club record summer buy Cavani has eight since joining from Napoli, and their quality was too much for Belgian champions Anderlecht, who remain without a point in the section and are staring at an early exit.
In contrast, the French club are beginning to look like genuine contenders to win the tournament for the first time, although they will face far stiffer tests than this in the months ahead.
"It was a really good game with plenty of positives all over the pitch. It was the perfect match," declared PSG coach Laurent Blanc.
"Ibrahimovic´s four goals were exceptional. It is difficult to say which was the best.
"Winning the Champions League would be a dream for all the players and the board. But it is a difficult objective. We need to go one step at a time and the first is to win the group."
Blanc named his strongest possible side, with the only notable absentee being captain Thiago Silva, who is still not fit again after a thigh problem.
The hosts young line-up included the 16-year-old Youri Tielemans in midfield, but they did not appear overawed in the early stages, seeking to take the game to PSG.
Salvatore Sirigu in the away goal had to turn a well-struck Matias Suarez shot around the post in the eighth minute, before Ibrahimovic managed to miss the target with just ´keeper Thomas Kaminski to beat at the other end.
That was a sign of what was to come, and the Swede - who appears to be on a mission to win the Champions League for the first time in his career - got the breakthrough after 17 minutes, easily tapping in a low Gregory Van der Wiel cross from the right at the back post.
The duo combined again to make it 2-0 five minutes later, the Dutch full-back´s low ball being back-heeled into the net in typical Ibrahimovic fashion at the near post.
It went from the sublime to the ridiculous as he completed his hat-trick, pouncing on a loose ball 30 yards out to hammer a ferocious first-time volley past a helpless Kaminski in goal.
Many home fans rose to their feet to applaud that effort, and it was already game over, but Anderlecht did not help themselves as they conceded again seven minutes after the restart.
Teenage Congolese defender Chancel Mbemba slipped, allowing Blaise Matuidi to square for Cavani to make it 4-0, before Ibrahimovic drove in his team´s fifth - and his 37th in the Champions League in 98 appearances - off a post just after the hour mark.
He might even have scored another but, with Kaminski off his line in the 76th minute, an attempted chip landed on the roof of the net, and he saw another shot saved towards the end.
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