Louis van Gaal's side trail league leaders Chelsea by 10 points after nine matches this season, but their situation could have been worse if not for Robin van Persie's stoppage-time equaliser against the Blues at Old Trafford.
He told reporters: "Chelsea was a huge result for us and when you look back at the game, maybe we could have got more than one point. We never give up and we showed that against them. That does a lot for our belief."
United face Manchester City in their next Premier League outing at the Etihad Stadium on Sunday.