Victory means the 29-year-old, world champion in 2010, is guaranteed to improve on the bronze medal he won at the Beijing Games four years ago.[break]
Having won the first period against Akzhurek Tanatarov of Kazakhstan, Kumar saw his semi-final opponent level and then go 3-0 ahead in the third and final period.
But Kumar countered with a hold down initially worth two points, which he converted into a three-point score to tie the match. And with 34 seconds left he´d edged 5-3 in front.
Then, with just seconds of the contest remaining, Kumar sealed victory with a huge throw that saw him dump Tanatarov onto the mat.
Now he will face Japan´s Tatsuhiro Yonemistu in the final later Sunday.
Kumar had a tough start to his London 2012 campaign, beating 2008 gold medallist Ramazan Sahin of Turkey 3-1.
There are no seedings in Olympic wrestling and the luck of the draw saw Kumar paired against fellow former world champion Sahin in the last 16.
In his quarter-final bout, Kumar overcame Uzbekistan´s Ikhtiyor Navruzov, also by a 3-1 margin, after surviving a spirited rally by his opponent with some quick counters and strong lifts.
Kumar, who carried India´s flag at the opening ceremony, is now assured of giving his country their second freestyle wrestling medal of this Games after Yogeshwar Dutt won 60kg bronze on Saturday.
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