The Gunners lost their hold on first place in the Premier League after their demolition at Anfield on Saturday, but their manager is confident that they will show their worth against United at the Emirates Stadium.
"It is always a disappointment to lose a game, but I think it was an accident because we have been very stable defensively and we have to treat it like that," Wenger told a press conference on Tuesday. "We have just been on a ten-game unbeaten run.
"You cannot consider one game as the trend, the pattern of our season. It is an accident, not a welcome [one] of course, a very disappointing one, but a successful season is decided by how you respond to that."
Wenger spoke out in defence of record signing Mesut Ozil, who produced an anonymous performance at Liverpool that was in keeping with some below-par recent displays.
"He didn't have the best of games on Saturday, but that can happen," the Frenchman said of the Germany playmaker. "He works very hard to adapt to the physical level of the Premier League and for me he is an exceptional player.
"I wouldn't like to put too much pressure on him because he has been a top-class player until now. He knows when he is not good enough, he will get questioned. That is normal."
Wenger is hoping that France U-21 forward Yaya Sanogo will be available to feature against United, having spent five months on the sidelines with a back problem.