The Arsenal boss admitted that he's still haunted by Ryan Giggs' extra-time goal that sent United to the final of the tournament, saying he can still hear the cheers of the jubilant winners.
"I can still hear the shouts of that team, having won," Wenger said. "They couldn’t believe it because they were down to 10 men. And I think that put them in a state of euphoria. In the same way, they won the title - just."
Arsenal looked destined to advance to the final when they won a penalty in the dying moments of regulation time. But Dennis Bergkamp's failed effort gave United new life and sent the match to extra time.
A misplaced pass from Arsenal captain Patrick Viera went right to the foot of Giggs, who masterfully advanced up the pitch, beat four defenders and fired the game-winning shot over David Seaman's shoulder.
United went on to win the tournament and capture the treble with triumphs in the league and Champions League.
"I saw that goal again when Giggs retired. I think that goal won them the treble because, if Bergkamp scores, I think the game is over," Wenger explained. "It was a trauma for us and a positive for them. That goal was certainly what decided their season."
While it can't erase the memories of that fateful night in Birmingham, Wenger and his squad can claim victory in what might be United's only chance for silverware this year, a clash Monday in the FA Cup quarterfinal at Old Trafford.