[alex18122003]

The facts and figures say Manchester United cannot fail to book a place in the semi-finals of this season's Champions League, but United know better than most that a great European comeback should not be dismissed out of hand.

Roma have a 2-0 deficit to overturn after goals from Cristiano Ronaldo and Wayne Rooney in Rome last week gave United a big advantage heading into tonight's game at Old Trafford.

It is an unenviable mission for the Giallorossi, and a quick glance at some telling statistics only serves to reinforce how difficult their task is.

United have lost just seven of 67 Champions League home games but none by the minimum two-goal margin that Roma need to reach the semi-finals.

Roma have won just once in ten previous visits to England - a 1-0 victory at Liverpool in the fourth round of the 2000-2001 UEFA Cup.

Only once have Roma come back to win, when they lost 2-1 at home to Nurnberg in the 1988-1989 UEFA Cup first round but then triumphed 3-1 in Germany.

United have been in this position 13 times before in European competitions, qualifying rounds included, and have never lost a tie after winning away in the first leg.

And United are one of just two teams, alongside Barcelona, who remain unbeaten in this season's competition