Do the two sides have what it takes to ensure that the semi-finals this year will feature three English sides?
PORTO v MANCHESTER UNITED (tonight 19.45):
Porto drew 2-2 at Old Trafford in the first leg last week, to pick up two vital away goals. In their Champions League campaign this season, they have won four, drawn three and lost two, scoring 13 and conceding 12 goals in the process. Porto will be without defender Jorge Fucile (ankle) for the match.
United's draw with Porto last week was their sixth of the campaign this season. They have won three others, scoring 13 goals and conceding five. They could welcome back Dimitar Berbatov and Rio Ferdinand from injury, as both are included in the squad that travelled to Portugal. Rafael and Anderson are also included, although they are still carrying minor injuries.
Prediction: United have still not recovered fully from their recent downturn in form, with their apparent defensive weakness still on show. They have conceded 12 goals in all competitions since the beginning of March, which is a far cry from the form that saw United go over three months (15/11/08 to 21/02/09) without conceding a single goal in the Premier League.