Pellegrini was speaking after City were beaten 3-0 by Arsenal in the Community Shield at Wembley where he selected summer signing Willy Caballero ahead of Joe Hart.
Caballero could do little to prevent the opening two goals from Santi Cazorla and Aaron Ramsey, but was caught off his line by Olivier Giroud’s impressive third on the hour mark for the Gunners.
Hart was watching on from the bench throughout the game, with Pellegrini not willing to reveal who would start Sunday’s Premier League opener at Newcastle, live on Sky Sports 1HD.
"The goalkeeper is the same as any other position - most of the players who played today played all of pre-season," he told City’s official website.
"All the 22 players in the squad are number 1 in all of the positions – we need them all.
"Joe finished last season playing very well – we will see next Sunday who starts against Newcastle.
Pellegrini admitted his side were made to pay for a sluggish first half at Wembley, with Arsenal two goals to the good by the interval.
"In this match, we had two different phases," he added. "In the first half we didn’t play with the pace we showed in pre-season and Arsenal scored two goals because we didn't defend very well.
"In the second half we played well, we had possession of the ball and had chances to score.
"It is always bad to lose but we don't need to worry – this was all about players engaging in the game rather than the all-round performance.
"It's difficult to be ready in two weeks. We'll see during the week which players are ready and which are not.
"We were missing key players but I think the lack of pace in the first-half was the main problem."