Jose Mourinho said he would have to be careful about choosing when to put Marcus Rashford in his starting line-up after the teenage striker stepped off the bench to score a stoppage-time winner at Hull.
Rashford made his first league appearance of the season when he replaced Juan Mata in the 71st minute and with United looking set for a frustrating draw that would have halted their 100 per cent start in the Premier League, the 18-year-old converted in the second minute of time added on.
Mourinho has clearly been impressed with what he has seen of Rashford so far, but insisted his striker's match-winning goal will make no difference as to how and when he will use him this season.
"He's very good," Mourinho said. "I know that he's very good since last season, but working with him every day I think the same.
"The two matches we were needing a winning goal against Leicester and tonight. He came on and gave us diversity in our football.
"He's different than (Wayne) Rooney, he's different than Zlatan (Ibrahimovic), so everybody is happy with him and we're happy with the squad."
Rashford, who burst on to the scene last season under previous boss Louis van Gaal and was rewarded with a place in England's Euro 2016 finals squad, will have thanked elder statesman Rooney for his winner.
Rooney ghosted round Hull full-back Ahmed Elmohamady before sending over an inch-perfect cross for Rashford to tap home from two yards.
"I have two weeks before the next match, I have to analyse the opponent and see the way my boys are coming back from the international games," Mourinho said.
"He can play but he can be on the bench, I don't know.
"I have to analyse. The important thing is that he's working very well. He's 18-years-old."
Mourinho added: "We are starting matches with a second man behind Zlatan, (but) we can start some matches with the player in front of Zlatan, so the kid is going to play a lot of matches for sure."
Mourinho, whose side is level with bitter rivals Manchester City and former club Chelsea at the top of the table after three straight league wins, revealed Marouane Fellaini could be sidelined after sustaining a back injury.
Meanwhile, United defender Luke Shaw already has one eye on his side's Premier League derby clash with City after the international break. "We want to win every game and this game is over now," Shaw said after the win at Hull.
"We've got to focus on the international break but obviously we have the big game against Manchester City when we come back.
"We know matches like that can help us win championships." Shaw said he had never felt so high on the pitch after Rashford's winner in the second minute of time added on had made it three wins from three in the Premier League.
"I think, emotion-wise, that was the best I've felt ever on a pitch," Shaw added.
"I'm just so happy that we could get the three points, not just for us but for the fans. They were unbelievable.
"It was an unreal feeling and even a few of the lads in there (the dressing room) said it was like taking them back to the old days when they sometimes used to get those smash-and-grab wins. I loved it and hopefully there's more to come."
Hull caretaker boss Mike Phelan is expecting a frantic few days before the transfer window shuts on Wednesday. He said: "We've made a great start and we need to back that up now with some new players, just to give us a helping hand to take us on and further."