But the result was desperately harsh on the visitors after a first half in particular of some spellbinding football.
Determination won us the game - Queiroz
Indeed, they should have put United out of sight - from the first whistle they seemed steadfastly determined to prove they were still in the title race and they played with a verve and a tempo United struggled to live with.
Cesc Fabregas was at his orchestral best and with Alexander Hleb, playing just behind Adebayor, constantly pulling defenders out of position, the chances soon started to flow.
Fabregas sent a shot narrowly over before Emmanuel Eboue crossed from the right and Adebayor's shot was superbly blocked by Rio Ferdinand.
Gilberto Silva saw a volley from a corner blocked by his own player, Alex Song, while Adebayor twice failed from promising positions on the edge of the box.
United's best chance of the half fell to Wayne Rooney after great work from Patrice Evra and Ronaldo, but his close-range shot was brilliantly diverted wide by the recalled Jens Lehmann in the Arsenal goal.
Moments later Hleb took possession in the United half, raced past Gerard Pique as though he was not there and teed up Adebayor 12 yards out, but his shot was tame and straight at Edwin van der Sar.
Rooney had another shot saved towards the end of the half, but Gunners boss Arsene Wenger must have wondered what his side had to do to score.
He was not to be disappointed for too much longer as Arsenal took the lead in controversial circumstances two minutes after the break.
Controversy - Adebayor appears to put the ball in with his arm
Robin van Persie took the ball down the left and split the United defence and keeper with a perfect delivery across the six-yard box that Adebayor appeared to bundle in with his left forearm.
United deserved to be behind, but Arsenal have recently become a team that looks afraid to be ahead and only four minutes later they were pegged back.
Hargreaves' ball into the box was inexplicably handled by Gallas and after his first penalty was ruled out for encroaching, Ronaldo slammed his second effort into the bottom corner.
Sensing blood, United sent on Carlos Tevez and Anderson, while Wenger replied with the introduction of Theo Walcott, under the watching gaze of England coach Fabio Capello.
Tevez almost made an immediate impact, his sizzling 25-yard strike flying inches wide of the Arsenal goal with Lehmann comfortably beaten.
After Gael Clichy's deflected cross was tipped onto a post by Van der Sar, United dealt a hammer blow to the Gunners' hopes of winning silverware this season.
Evra was tripped 25 yards out and Hargreaves stepped up to delightfully clip the ball up and over the wall and into the unguarded corner of Lehmann's net.
Van der Sar saved late on from substitute Nicklas Bendtner as United held on for a victory that may well secure them yet another Premier League title.
Man Utd: Van der Sar, Brown, Ferdinand, Pique, Evra, Ronaldo, Carrick, Hargreaves (Giggs 89), Scholes (Anderson 55), Park (Tevez 55), Rooney. Subs Not Used: Kuszczak, O'Shea.
Booked: Brown, Carrick.
Goals: Ronaldo 54 pen, Hargreaves 72.
Arsenal: Lehmann, Toure (Justin Hoyte 85), Gallas, Song Billong, Clichy, Eboue (Walcott 61), Fabregas, Silva, Hleb, Van Persie (Bendtner 76), Adebayor. Subs Not Used: Djourou, Fabianski.
Booked: Van Persie, Gallas, Lehmann, Adebayor, Justin Hoyte.
Goals: Adebayor 48.
Ref: Howard Webb (S Yorkshire).
BBC Sport Player Rater man of the match: Manchester United's Wayne Rooney 7.26 (on 90 minutes).
Please note that you can still give the players marks out of 10 on BBC Sport's Player Rater after the match has finished.
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