The Spain striker had missed a string of chances before he ran onto a quickly taken free kick from Cesc Fabregas, cut inside a defender and curled a shot into the far corner in the 64th minute.It ended Costa's six-game scoring drought in all competitions and allowed Mourinho — back in the dugout after a stadium ban — some breathing space after Chelsea's consecutive losses to West Ham, Liverpool and Stoke.
Chelsea started the game in 16th place after the worst start to the season by a Premier League champion, and there were chants of "We are staying up" and "Jose Mourinho" at Stamford Bridge by the final whistle.
Costa had failed to get on the end of two crosses by the lively Eden Hazard and had also wasted two more chances before scoring his third league goal of the season.
"If he did not score, it would be a big 50 kilo on his back," Mourinho said, "but he scored and he could breathe easy. If the result is fake, it is fake because we should have scored more goals."
Kurt Zouma hit the bar with a shot soon after Costa's goal and Nemanja Matic waltzed through on goal, only to be denied by John Ruddy, as Chelsea showed some of the swagger of last season.
"Me and the fans didn't deserve to have our heart in our hands in the last four minutes," Mourinho said. "It is the pressure of the bad results, that is normal, but they coped well."
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