Arsene Wenger's final visit to Old Trafford ended in defeat through a classic 'Fergie Time' goal from substitute Marouane Fellaini. Wenger - stepping down at the end of the season - was presented with a silver trophy before kick - off by Messrs Mourinho and Ferguson, in recognition of his 22 years of unstinting service with rivalries put aside and old feuds forgotten. With the priority Thursday's Europa League semi final second leg with Atletico, he named a much - changed Gunners side but it was one that acquitted themselves well.
Fellaini's header in the first minute of stoppage time, though, condemned the visitors to a sixth successive away league loss, and moved United five points clear of Liverpool (with a tie in hand), in the battle for second spot. Arsenal - without a single point away from home in 2018 - saw their already very slim hopes of a top four finish mathematically ended by this result.
Paul Pogba had given the Reds an early advantage, cancelled out by Henrikh Mkhitaryan on his first return to Old Trafford with his new club. But Fellaini, with his Old Trafford future still yet to resolved, popped up with the winner to poop Wenger's farewell party and saw Jose get one over on his old foe one last time.
Pogba put United ahead in the 16th minute, as he started and finished a flowing move. The Frenchman stroked the ball to Romelu Lukaku, whose cross was met by ex-Arsenal man Alexis Sanchez. His hopes of a dream goal against his former employers were dashed as his deflected header came off a post, but fell kindly for Pogba who snaffled up the rebound.
Ashley Young's cross - shot rattled the crossbar shortly before the interval, before United suffered a blow when Romelu Lukaku limped off with a foot injury on 50 minutes with the FA Cup final on the horizon. Almost immediately, the youthful Arsenal side were level, inevitably through Mikki, who swept home beyond David de Gea having been played in by Granit Xhaka. The Armenian did not celebrate.
Another former United man, Danny Welbeck, went close from distance soon afterwards, and Chris Smalling - on a fine recent run of form in front of goal - narrowly failed to connect with Anthony Martial's probing pass at the other end. Old Trafford erupted three minutes from time, only to be doused when Rashford was flagged offside after he bundled home off a post from Fellaini's knock down.
That looked to be the final chance of a low - key encounter, but the dissapointment was short - lived as the Reds, as they have done so often this season, again found a way to win it. A similar move down the left reaped the rewards as Young's teasing cross was met by the burly Belgian who diverted his header beyond the helpless David Ospina from five yards.
Although Champions League qualification for next season has long since looked certain for United, this result rubber - stamped it. The Reds have a Friday night trip to Brighton to look forward to, with three league games left before the small matter of that cup final vs Chelsea on the 19th.
Overall team performance: 7/10
United Faithful Man of the Match: Ashley Young. A constant menace with his surging runs and dangerous supply of bullets.