Manchester United manager Sir Alex Ferguson was delighted with Robin van Persie's impact off the bench in a 2-0 win over West Bromwich Albion.
The Dutchman sealed a nervy win at Old Trafford with his 17th goal of the season having been preserved for the first 65 minutes of the match.
"He is a fantastic player," Ferguson said.
"He came on and changed the game for us. Every time the ball came up to him he got hold of it and turned on them."
Ferguson was pleased with his side's work against Steve Clarke's resilient defence, who have been easier to break down away from home than at the Hawthorns.
"They (West Brom) were having to go back to their box all the time and he has done well," he said.
"They were a very resilient, stubborn team. They worked really hard on their defending and closed all their ranks.
"You have to deal with that but the slowness of the pitch killed our speed a bit."
United head to rejuvenated Wigan on New Year's Day and Ferguson said he would take that opportunity to freshen up his squad.
"Hopefully we can freshen up again. Possibly Phil Jones will be ready and Rafael will be ready," he said.
"We rested Javier Hernandez, and also Ryan Giggs and Paul Scholes, so we have enough freshness to bring in."
West Brom manager Clarke remained upbeat after the loss and felt the match could have gone either way when Ferguson opted to bring on his 'big guns' in the second half.
"There was a stage in second half when we had a really good control. I thought the game was more likely to go 1-1 than 2-0," Clarke said.
"The fact they had to bring some of their big guns off the bench shows how well we were doing."