Ospina has played every round of the competition so far, as well as Arsenal's matches in the FA Cup and the Champions League, and Arsene Wenger will likely opt to do the same again on Sunday.
Cech won three League Cups with Chelsea, but says it is hard to be a spectator.
"At the start it was clear that it was going to be like that," said Cech. "I will be there with the team supporting but I don't expect to play. It is always hard to watch any game from the bench or even from the stand if you are not selected.
"As a player, you always want to be involved. But obviously you are in a professional club where there are 25 top players and the manager always makes his choices for the game and you need to accept that," he continued.
Man City were targeting a quadruple before their shock loss to Wigan in the FA Cup on Monday night and they now face the prospect of being knocked out of two cup competitions in a week. Arsenal haven't won the League Cup since 1993.