David Moyes backed Danny Welbeck to play a key role in Manchester United's bid to retain the Premier League title after the England striker sealed his side's 1-0 win at Norwich.
Moyes had been unable to pick either Robin van Persie or Wayne Rooney because of injury and initially rested Welbeck on the bench at Carrow Road on Saturday.
But the 23-year-old came on to net the only goal of the game in the 57th minute as United sealed their sixth successive victory in all competitions.
The reigning champions are up to sixth, two points short of a top-four place heading into the new year.
Welbeck outshone Mexico striker Javier Hernandez, who had started, and Moyes was quick to praise his impact.
"If you look at Danny now, he is a big part of Manchester United," Moyes said.
"Obviously his goal made the difference but Danny's performance changed the game.
"We would have started him but he has played a lot of games and we are trying to make sure that we give the squad the right opportunities to play and make sure we give them chances to show what they can do.
"Danny has been playing very well and came on to make the difference
Welbeck's goal, the result of a double deflection of an attempted clearance by Norwich defender Ryan Bennett, was his 10th of the season and his seventh for United.
That already represents a better haul than last season, when he contributed just two goals for his club, but Moyes believes he can become even more deadly in front of goal.
"He is a really good player and what he needs to become now is a really good finisher," Moyes added.
"Today he rounded the goalkeeper and was unlucky with one which came to the far post and was not able to get a finish away there.
"Danny played really well at Hull the other day but he just looked a bit fatigued and so we decided not to start him."
Rooney, who has a groin strain, is expected to be available for United's home game with Tottenham on January 1, while Moyes indicated Van Persie's long-awaited return from a thigh problem was not far away.
"We have not had them as a partnership very often and we are looking forward to having them together," Moyes said.
Norwich made United work hard for their victory but the defeat followed a disappointing home loss to Fulham on Boxing Day, leaving them vulnerable to being sucked into the relegation dogfight.
"That's the massive disappointment -- it's certainly a game we didn't deserve to lose," said Canaries manager Chris Hughton.
"We were excellent in the first half but that's the game. When you are having your best period you have got to capitalise on that, and we didn't.
"It was a fortunate goal for them, a double deflection, and when that falls to somebody of Welbeck's quality then you are almost expecting him to score.
"That was the only difference between the two teams. Over the 90 minutes we were the better team."