Manchester United boss Sir Alex Ferguson says they risk being knocked out of the Champions League ahead of their clash with Benfica.

Ferguson is wary of a potential upset and has challenged his side to make life easier by taking all six points from the two remaining games.

"We showed a bit of carelessness against Basel but we are joint top with Benfica," Sir Alex warned. "FC Basel have got five points though so it's still not over, if you look at all of the different scenarios we can still beat Benfica and go out.

"As stupid as it may seem, if Basel were to go and wallop Otelul Galati and then beat us, they'd be on the same points as us and could knock us out on goal difference, unless Benfica can score enough goals against Galati in their last game. If they do then we are out, so it is interesting.

"The most important thing is to qualify but it is always that little bonus if you are top because then you avoid the likes of Real Madrid and Barcelona. Barcelona might not finish top, though, as they've got to go to Milan who have been doing alright."