Which is why the "if we play like that against..." comment is unnecessary; doubly so because most teams won't enjoy the kind of luck Celtic did on their goals.
Also, having watched the game a second time, I think our defending was decent for most of the game: as I said earlier in thread, most of their efforts on goal came in the first 15 minutes and after their third, they didn't get near Bravo. Their total number of shots was less than one more than the average number we have been conceding this season.
No one is pretending it was our finest hour or that the team needs to improve but performances will go up and down; let's hope they are up against Spurs or, yeah, surprise, surprise, we will get dicked if we do not play well.