And any fears boss Sir Alex Ferguson may have had about a hangover following their Champions League semi-final victory against Barcelona on Tuesday were dispelled by a vibrant performance.
If United were craving a fast start and an early goal, they could not have wished for more generous defending on the part of West Ham that gave them the lead after three minutes.
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Ronaldo escaped the attentions of Neill, and the rest of the Hammers' defence stood off as he raced into the area and beat Robert Green with a deflected shot.
West Ham were almost allowed a route back into the game three minutes later when United keeper Edwin van der Sar was uncertain and Patrice Evra had to clear off the line from Bobby Zamora.
And the visitors had appeals for a penalty waved away when Wes Brown handled under pressure from Zamora, but referee Mike Riley gave a foul against the West Ham striker.
United doubled their lead after 24 minutes when West Ham failed to deal with Owen Hargreaves' long cross and the ball went into the net off Ronaldo's thigh at the far post for his 40th goal of the season.
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Tevez made it three against his former club two minutes later when he sent a vicious swerving drive high past Green from 25 yards.
West Ham looked dejected and beaten, but Ashton gave them a measure of hope with a spectacular overhead kick after 28 minutes.
And the lifeline was extended further 10 minutes before the interval when Nani inexplicably head-butted Neill after a minor fracas - an offence made worse by the Manchester United winger hitting the ground holding his head in a desperate attempt to avoid punishment.
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Ashton injured a muscle in scoring his spectacular goal and it was no surprise when he went off early in the second half, to be replaced by Carlton Cole.
West Ham were in no mood to take advantage, however, and desperate defending allowed Carrick to stride forward unopposed to send in a deflected shot from 25 yards for United's fourth after 58 minutes.
It was now damage limitation for Alan Curbishley's side and an opportunity for United to improve their goal difference even further.
And United substitute Darren Fletcher almost added a fifth with 20 minutes left, only to see his angled drive come back off an upright.
The rest of the game was played out in a carnival atmosphere as Old Trafford anticipated another title triumph.
Man Utd: Van der Sar, Hargreaves, Brown, Ferdinand, Evra, Nani, Carrick, Scholes (O'Shea 72), Park (Giggs 61), Ronaldo (Fletcher 64), Tevez. Subs Not Used: Anderson, Kuszczak.
Sent Off: Nani (37).
Goals: Ronaldo 3, 24, Tevez 26, Carrick 59.
West Ham: Green, Pantsil, Tomkins, Neill, McCartney, Noble, Parker, Mullins (Sears 75), Boa Morte (Solano 52), Ashton (Cole 56), Zamora. Subs Not Used: Walker, Collison.
Booked: Neill, McCartney, Zamora.
Goals: Ashton 28.
Ref: Mike Riley (Yorkshire).
BBC Sport Player Rater man of the match: Manchester United's Cristiano Ronaldo 8.77 (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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