Charlton manager Curbishley reckons the pitch is proving problematic again.
"The pitch is not doing them any favours," he said. "It is very sticky and bobbly and not conducive to the type of football United like to play. But when you look at their squad, if they click they can cause any team damage and you could be looking at a very different situation in a couple of months."
"United are quite capable of putting a run together," added Curbishley.
"They were unfortunate not to get a goal against Manchester City a couple of weeks ago. If they had done, it would have been three wins on the trot now and they would have been on their way. They have whittled away leads like this before and I certainly won't be writing them off."