In-form Marcus Rashford stepped off the bench to earn Manchester United a 1-0 victory over Wolverhampton Wanderers on Saturday, a win that moved Erik ten Hag's side into the Premier League top four.
Ten Hag left the club's top goalscorer on the bench from the start due to an "internal disciplinary issue", and saw his team struggle to break down Wolves in the opening period, youngster Alejandro Garnacho wasting the visitors' best chance.
Rashford came on for the second half to give United more cutting edge in attack, showing great strength and composure to hold off his marker and fire the winner 14 minutes from time.
The England forward had another ruled out for handball late on, but it mattered little as United saw out their third league win in a row to move above Tottenham Hotspur, who play Aston Villa on New Year's Day, and into fourth. Wolves stay 18th.
"He (Rashford) was bright, he was lively and he scored a goal to give a good reaction," Ten Hag told BT Sport. "Everyone has to adhere to the rules and if you react like this, it is the right answer.
"We were not that good in the first half. In my opinion the second half was better. I was not happy at halftime and I told them with this attitude they will not win this game and everyone had to give 10 per cent more."
Fresh from their biggest league win of the season last time out – a 3-0 success over Nottingham Forest – United did not make the most of their first-half opportunities at Molineux.
Casemiro's header was deflected over early on, before Garnacho was denied by a superb save from home goalkeeper Jose Sa after Nelson Semedo's defensive error.
French forward Anthony Martial should have done better from a close-range header late in the half, but failed to make a clean connection.
Ruben Neves finally tested David de Gea in the United goal early in the second half, with his free-kick brilliantly kept out by the Spaniard, before the visitors resumed their control of the contest.
More chances came and went before Rashford fired his 10th goal of the season in all competitions after holding off Wolves' substitute Jonny and lashing the ball home from close range.
De Gea was called into action to deny Wolves a point in coach Julen Lopetegui's first home league game in charge, but United continued their improvement under Ten Hag with another victory.
"The goals are coming after good work and we are working as a team in and out of possession," Lopetegui said.
"Maybe we didn't have the best decision making in the box. We had five or six good situations to damage them but we had good chances."