A lacklustre game at Old Trafford was drifting towards a goalless draw when Mata collected a pass from Oscar and dispatched a low shot that took a slight deflection off Phil Jones on its way into the bottom-right corner.
Mata’s goal means that Chelsea will now go into Wednesday’s crunch clash against Tottenham Hotspur at Stamford Bridge with a three-point lead over their London rivals, who are bidding to crash into the top four.
Arsenal are sandwiched between the pair in fourth, a point behind Chelsea, having played a game more. Meanwhile, Everton remain on course to finish above Liverpool for the second season in a row after holding their city rivals to a 0-0 draw in a scrappy Merseyside derby at Anfield earlier in the day.
Photos: SRK does garba, Nawazuddin takes 'shower' in bathtub
Photos: Soha Ali Khan, Evelyn Sharma, Urvashi Rautela at Mumbai airport
Spotted: Lara Dutta, Mahesh Bhupathi with their daughter in Bandra
Photos: SRK, Tamannaah Bhatia, Varun Dhawan at Mehboob Studio
Birthday special: Sushant Singh Rajput's journey from TV to films