Michael Carrick sang the praises of David de Gea after the Spaniard made a string of late saves to deny West Ham and send Manchester United into the FA Cup semi-finals.
Goals from Marcus Rashford and Marouane Fellaini looked to have secured a comfortable passage into the last four for Louis van Gaal's men, but West Ham mounted a late comeback.
James Tomkins pulled a goal back but a second was not forthcoming thanks to the efforts of De Gea as United held on for a 2-1 win.
Spain's number one denied Andy Carroll twice in the closing minutes, before making a reflex save to keep Cheikhou Kouyate's effort out.
"He's been unbelievable for us for so long now," Carrick said of De Gea when asked by BBC Sport.
"We needed him at the end. The goal gave them incentive. We defended well at times but David stepped up."
Victory puts United into a last-four tie against Everton on April 23, and keeps Van Gaal's men in with a chance of silverware in what has been a frustrating campaign.
"It [the win] was massive. A great opportunity for us to get to Wembley," Carrick added.
"West Ham are flying and it's a tough place to come. We believed we would come here and win and we have done that.
"We have had some terrific results and some bad ones [this season]. That's something we have tried to put right. We need to be consistent and that's the challenge we have to set ourselves."