Moyes rotated his squad following the 4-1 defeat against Manchester City and is not afraid to drop his stars.
They bounced back with a win against Liverpool in the League Cup, but Moyes insisted that no-one is guaranteed to play.
"There is a squad," Moyes told reporters. "You use the word rotation, but I want to see good form.
"Whatever Sir Alex Ferguson had done before, you had to perform. He used players at the right time and I will try to do the same.
"But our performance against City didn't merit people necessarily thinking they would play in the next game."
United take on West Bromwich Albion at 3pm on Saturday.