Alan Smith says United's Champions League massacre of Roma was vital to the Reds' hopes of ending the season with silverware.
Back to back defeats - in the first leg against Roma and on Saturday at Portsmouth - had raised question marks over how United would see out a thrilling season.
But the 7-1 mauling of the Italians, in which Smith scored his first goal since November 2005, demonstrated the squad's resolve and belief.
"I think for Manchester United it was vital," he told ITV Sport. "It was a massive night for us in terms of how our season would progress, to be honest.
"I think everyone knew that before the game. We came out of the traps flying and blew them away."
The fit-again striker, who was back to his abrasive best against the Giallorossi, now expects United to kick on for the remainder of the campaign.
"It gives us a massive lift," he said. "After the first Roma defeat and the defeat at Portsmouth, a lot of people thought that we were a young squad with not a lot of experience in terms of winning things.
"I think tonight showed we are up for that fight."