Brighton staged a superb fightback from two goals down to beat Manchester City 3-2 after the champions had Joao Cancelo sent off.
Supporters have been allowed back into Premier League matches this week for the first time since December.
A limited number of fans had attended the League Cup final and the FA Cup final in April and May respectively, as well as one of the FA Cup semi-finals.
All of those matches were staged at Wembley, but the Premier League had delayed the last two rounds of fixtures to take advantage of the UK's easing of coronavirus restrictions.
Around 7,900 saw Brighton's dramatic revival against City, with 10,000 United fans present at Old Trafford and 8,000 at Southampton for their 2-0 defeat against Leeds.
With the title wrapped up, City are fine-tuning their preparations ahead of the Champions League final against Chelsea in Porto on May 29.
But Pep Guardiola's side were beaten for the second time in their last three games after a second half collapse at the Amex Stadium.
Ilkay Gundogan headed City into the lead from Riyad Mahrez's second minute cross.
But Cancelo saw red in the 10th minute after the City defender hauled down Danny Welbeck.
Phil Foden increased City's lead in the 48th minute with a fine solo effort, only for Leandro Trossard to get one back moments later.
Adam Webster equalised with a thumping header in the 72nd minute before Dan Burn grabbed the winner from close-range four minutes later.