"Offensively wasn't a problem, we attacked very well and Paul Robinson has had as much to do as our keeper," the Fulham boss told Sky Sports News.
"We defended very poorly, you can't defend like that against that type of quality against a team where they've got a player of Berbatov's quality on the bench.
"We had as much possession as them and at 1-0 we were always in the game, pushing it in the second half.
"It's the FA Cup, we don't want a replay, we wanted to finish the tie off and even at 1-0 we were pushing and creating opportunities.
"But if you're at home, I don't care who you are playing against - 4-0 is 4-0, let's not make any excuses about that.
"You can't concede four goals at home, whether you are playing Man Utd, Tottenham or whoever, and that hurts."
