The Red Devils defeated Japanese club Gamba Osaka 5-3 in an all-out attacking affair and Ferguson believes van der Sar saved the day.
"It was a terrific match, an amazing game, the people got their money's worth," Ferguson said.
"The football from both teams was very good. For me Edwin Van der Sar was our best player, his saves helped secure the victory for us.
"We are in the final and I think we deserve to be there."