Joey Barton's late equaliser gave Manchester City a point at Old Trafford and ensured they maintained their good start to the season.
Ruud van Nistelrooy gave United the lead in first-half injury time, turning home from close range after David James had saved his first effort brilliantly.
But United failed to take advantage of their supremacy, with Van Nistelrooy and Park Ji-sung missing chances.
And Barton struck after 75 minutes, turning home Darius Vassell's effort.
United rested Roy Keane and Ryan Giggs, giving Keane's central midfield slot to Alan Smith, while Park got the nod on the flank.
City kept United at arm's length for much of the first half, although they did not create any chances of their own.
Park worked an opening after 10 minutes, but shot across the face of goal, then Van Nistelrooy turned a close-range effort over the top after the South Korean had turned on John O'Shea's cross.
And just as City looked to have safely negotiated the first 45 minutes United took the lead in controversial circumstances in time added on by referee Steve Bennett.
Paul Scholes powered in a free-kick, but when James saved brilliantly from Van Nistelrooy's instinctive flick the Dutchman hammered home the rebound with City appealing furiously for offside.
City's Claudio Reyna was booked in the ensuing exchanges, but television replays suggested the officials had correctly ruled that Van Nistelrooy was onside when he scored.
United continued to control the game after the break, dominating possession and territory almost completely, and it needed desperate work by Sylvain Distin and Richard Dunne to prevent them extending their advantage.
But with 15 minutes left, resilient City pounced to snatch an equaliser.
Former United striker Andy Cole was involved, firing in a shot that was well saved by Edwin van der Sar, but when Vassell fired in the rebound Barton was perfectly placed to apply the vital touch.
United had sent on Giggs in a bid to grab all three points, and it almost work as he flashed a header inches wide with James well beaten.
But it was City who almost had the last word, when Van der Sar produced a stunning fingertip save to deny Cole when he fired in a powerful drive from Trevor Sinclair's cross.
Man Utd boss Sir Alex Ferguson:
"They didn't deserve what they got, but that's football.
"We could have scored two or three more and we were a bit unlucky. We needed the second goal because there was always going to be some point where they had a go, and they scored with their first shot.
"In the end it took a great save from Edwin van der Sar to stop Andy Cole getting the winner, which would have been a ridiculous scoreline.
"We've had quite a tough programme, but the team is playing well and there is good confidence and a great team spirit."
Man City boss Stuart Pearce:
"Hopefully we are built on a more organised foundation and the players are starting to believe that if you do the right thing you get your rewards.
"We don't want boom and bust at this football club, either in transfer policy or on the pitch. I want steady progress.
"The players must know exactly what they are doing from the first minute to the last. We are the poor relations in this city in terms of finance, but we are not poor relations in terms of team spirit."
Man Utd: Van der Sar, O'Shea, Ferdinand, Silvestre, Heinze, Fletcher (Keane 78), Smith (Richardson 87), Scholes, Rooney, van Nistelrooy, Park (Giggs 81).
Subs Not Used: Howard, Bardsley.
Booked: Van Nistelrooy.
Goals: Van Nistelrooy 45.
Man City: James, Mills (Jihai 72), Dunne, Distin, Thatcher, Sinclair, Barton, Reyna, Musampa (Sibierski 72), Vassell (Fowler 84), Cole.
Subs Not Used: Weaver, Onuoha.
Booked: Cole, Thatcher, Reyna, Mills.
Goals: Barton 75.
Ref: S Bennett (Kent).