He cut an unusual figure on Sunday, walking off on his own toward the Old Trafford tunnel: jeered by the Manchester United fans, too unpopular to risk going anywhere near the Chelsea fans. Rafa Benitez was on his own again but life at Chelsea can rarely have felt so good for him.
A win secured in the last three minutes of normal time means that a victory over Tottenham Hotspur on Wednesday will deliver Chelsea the Champions League football that Benitez was tasked with delivering when he took over the club in November. Throw in the Europa League final in nine days' time and you understand why some pragmatists in the Chelsea hierarchy think that he would make a good long-term manager if it were not for, well, you know what.
A dreadful game with a rousing conclusion, Mata's shot found its way in past Anders Lindegaard via Phil Jones before Rafael Da Silva was sent off for a very unwise kick aimed at the back of David Luiz's legs in the closing stages. A setback for the young United right-back who has matured considerably this season but at least you could call it progress of sorts. He used to get sent off in games of note, at least now he confines it to the ones that do not matter.
Unfortunately for Arsenal and Tottenham Hotspur, who desperately needed United to stop Chelsea winning at the very least, Sir Alex Ferguson's team have run out of steam. Even before they secured the title a fortnight ago today they had already been on the decline for a while and now they are simply going through the motions. If Arsène Wenger hoped for something in return today for the sale of Robin van Persie, then he will have been disappointed.
Ferguson's own indictment of his team's performance said it all. They had, he said, "taken their foot off the pedal" there was "no edge". That he would blithely admit to that said it all really, United are cruising to the end of the season and there is little that anyone, including their manager, can do to change that.
It will be painful for Chelsea's two London neighbours who are trying to compete for the last two Champions League places but even so, you have to admire the steel of this team. Last season they rescued a Champions League place by winning the damn thing; this season they have fought their way back into contention. That refusal to let it go characterises this squad.
Beat Spurs on Wednesday and Chelsea's superior goal difference will surely see them through to one of the two Champions League places, whatever happens in the final two matches of the season. As for Benitez he has eliminated United from the FA Cup after a replay and now beaten them at Old Trafford in the league – it would be unbearable for his old foe Ferguson were it not for that trophy awaiting his collection on Sunday.
Ferguson bemoaned Howard Webb's performance but it was Chelsea who felt the most aggrieved by the referee until the closing stages. Yet even Ferguson did not complain about the tackle on Wayne Rooney, a second-half substitute, that began the sequence that ended with the heavily deflected winner.
It was a tidy challenge from Ramires to hook the ball away from Rooney on the edge of the area, and there was contact, although it looked more like the United man running his leg into his opponent. While Chelsea moved the ball forward quickly, United did briefly win it back and then lose possession again before Ramires, tireless, got it back and, via Oscar, the ball reached Mata on the left side of the box.
The Premier League, grumpy killjoys that they are, gave it as a Jones own goal just minutes after the end of the game. Replays were inconclusive but Mata's shot did seem to be running wide of Lindegaard's left post before it flicked off the United man and into the far corner of the goal.
The red card incident between Rafael and Luiz took place right under the nose of Sian Massey, the assistant, who correctly judged that the nasty little kick by the younger Brazilian was a dismissal. In mitigation, Luiz twice thrust an elbow into the chest of his opponent as he stepped across him, attempting to shepherd the ball out of play.
In the aftermath, while still on the ground, Luiz appeared to crack a smile. What he meant by it was hard to divine. It may have looked a bit sneaky but it did not change the fact that Rafael, however much he had been provoked, had lashed out in a fashion that was certain to earn him a red card. It was his fault. Oscar did not help himself by waving imaginary cards. That set off Ryan Giggs who risked a booking himself by waving imaginary cards in an attempt to show Webb what Oscar's transgression had been.
By that stage we were already in injury time and United's sudden desperation to win the game seemed a bit too late to be taken seriously. They had barely created a chance in the entire second half.
Instead, the biggest moment before the goal had fallen for Mata who had failed to get his head on a very inviting cross from the right by Frank Lampard. That was about as good as it got, although one break in which Chelsea outnumbered United's defenders was well stopped by Jones' tackle on Ashley Cole.
On the touchline, John Terry, also left out the side for the Europa League semi-final second leg on Thursday found himself a peripheral figure once again. He will be desperate to play against Spurs on Wednesday but there are no guarantees. There was no contact between him and Rio Ferdinand, also an unused substitute yesterday, but Rooney stopped for a chat while Terry stretched by the side of the pitch.
Petr Cech scarcely had a shot to save all match, with or without Rooney on the pitch. Lindegaard pushed an Oscar shot on to the post in the 14th minute. Jonny Evans was lucky to get away with grabbing Demba Ba's shirt shortly afterwards. It was the first time that United had failed to score in the league since December 2009. Chelsea were far from perfect but, as Benitez knows, it is the wins that count.
Goal. Chelsea: Jones og 87
Substitutions: Manchester United Buttner 5 (Cleverley, 68), Rooney 5 (Anderson, 69), Hernandez (Valencia, 90). Chelsea Torres (Moses, 76), Ake (Mata, 90).
Booked: Manchester United Vidic, Jones. Chelsea Luiz.
Sent-off: Manchester United Rafael (89).
Man of the match Mata. Match rating 7/10.
Possession: Manchester Utd 51%. Chelsea 49%.
Attempts on target: Manchester Utd 4. Chelsea 6.
Referee H Webb (South Yorkshire).