Manchester United boss David Moyes admits last weekend's derby defeat has given him doubts over some of his first choice players, insisting he will drop those who perform inconsistently.
The 4-1 humbling at the hands of Manchester City has prompted Moyes to consider making further changes to his side ahead of Saturday's clash with West Brom.
Although the Scot denies he is opting for a rotation system this season, he has placed significant pressure on his side to perform.
"There is a squad," he said. "You use the word rotation, but I want to see good form. If you play, it makes the job much easier. You've got to play and you've got to play well.
"Whatever Sir Alex Ferguson had done before, you had to perform. He used players at the right time and I will try and do the same. But our performance against City didn't merit people necessarily thinking they would play in the next game."
One player who is likely to be given a chance to impress is Belgian winger Adnan Januzaj, who has attracted interest from Manchester City and Juventus.
Moyes is confident Januzaj's future remains at Old Trafford and is hopeful the 18-year-old can establish himself as a regular this season.
"We really think an awful lot of Adnan," Moyes added. "He's a Manchester United player and I'm sure he will be. We think this is the best place for producing and giving young players an opportunity.
"It's part of my remit to promote young players and Adnan has been promoted already. The next part is to become a regular first team player. He's keen to stay but he has some influences around him."