Reading manager Brian McDermott says keeper Adam Federici was dropped for Sunday's game against Tottenham because of poor form and not due to injury.
Federici had made mistakes in both of Reading's opening two fixtures.
The Australian keeper had been injured, but McDermott says it was form and not fitness that prompted his decision.
"I really like Adam and he works very hard but things have not gone his way, so Alex has come into the team," McDermott told BBC Radio Berkshire.
Reading 'will learn from mistakes'
Alex McCarthy played in place of Federici at the weekend and pulled off a string of decent saves, although
Reading were beaten 3-1 by Spurs.
And McDermott says he is not afraid to drop any player if they are not performing at their best.
He added: "The fact of the matter is, I spoke to Adam on Saturday and I made a decision that Alex McCarthy was going to play in the game on Sunday.
"No player at the club is in a position that means they will play every week.
"Adam Federici has done fantastically well for me and I know him really well, but he is no different to a full-back or centre-half or striker."
Federici had pulled out of international duty with Australia earlier in September but Reading's manager has confirmed the 27-year-old believed he was fit to play.
And the Australian's girlfriend later took to Twitter to criticise the decision to drop him.
"The grey area was, I spoke to Luke Anthony (first-team physio) who says he had an issue with his knee which needs to be sorted out, rehabilitated," McDermott continued.
"Adam does not see it that way. He wants to be back in the squad and fighting for his place and not being on the bench."