The Reds' assistant manager told MUTV that the squad's continuing pursuit of two trophies - a 20th league championship and 12th FA Cup, both of them competition records - will ensure the players and coaching staff swiftly snap out of any gloom following the painful last-16 defeat to Real Madrid in the Champions League.
"The atmosphere in the dressing room was very, very solemn," admitted Phelan, "and the players are down because they felt as though they had carried out the tactics, showed their abilities, got the goal that we needed to get at a great time and felt in control.
"But this loss was not of our own making so why should we be down and despondent when we've got everything to work hard for and everything to achieve?
"We've still got an FA Cup tie [on Sunday, against Chelsea] and we're still in a commanding position in the league. So we'll get over it, we'll bounce back."
The controversial 2-1 reverse to Real Madrid at Old Trafford was the Reds' first meaningful defeat since losing 1-0 at Norwich City on 17 November, given that the two losses at the hands of Galatasaray and CFR Cluj were both in the Champions League after a last-16 place had already been confirmed.
After that autumn shock at Carrow Road, United won the next five matches in the Barclays Premier League and Phelan said, "This is something Manchester United do - we lose a game and then we come back after a defeat.