We haven't often had to come from behind to win a game, but out of the 5 games (in 33 games) we've gone a goal down, we've failed to win 4 of them, losing 3 of them. Ironically the one game we did win was the league game at the Etihad. But if there is a question mark (or weakness) over this team it's our ability to win a game from a losing position.
Your injury issues is of course a concern for you, but I still think whatever team Pep puts out there won't be a team that's inferior in quality to Chelsea.