The veteran keeper produced a series of top-class saves to keep Fulham in the tie at St Andrew's before fellow Welshman Mark Pembridge popped up with his first goal since March to send Fulham into the 4th round and an away tie at Nottingham Forest.
"We've played a lot better than that this season and lost," Coleman said after the game.
"If we play like that again on Saturday against Spurs I'll settle for that because we are in a dogfight down at the bottom of the league.
"Mark Crossley was outstanding for ninety minutes. We could have easily been 4-0 down at half time but he played so well.
"We were on the ropes a bit first half but we came out second half and we showed a bit more in our play and Mark Pembridge scored a great goal.
"He's been a consistent player since he's come into the team this season and we're delighted for him."