The Gunners have appeared in UEFA’s elite club competition in every season under Wenger from 1998-99 onwards, but are facing the prospect of finally missing out next term.
Arsenal lost 2-0 at London rivals Tottenham last weekend to sit sixth in the table, five points behind United and six back from fourth-placed City, although they do hold in a game in hand on both.
Addressing the media ahead of United’s visit to Emirates Stadium, Wenger was unequivocal in stating the importance of the clash.
“More than focusing on Manchester United, what is important is having a chance to achieve our target,” he said. “There is no choice, we have to beat them.”
Previously a match that often decided the destination of the title, Wenger feels the fixture’s diminished status is an indication of the fierce competition between the Premier League’s heavyweight teams.
“It just shows everybody has moved up,” said the Frenchman.
“There are a number of clubs who can fight at the top and the difference between the teams is smaller. As soon as you are not at your best you can lose.”
The game marks a resumption of hostilities between Wenger and United boss Jose Mourinho, who have experienced a fierce personal rivalry, bordering on the genuinely unpleasant at times.
“I do not make of it a manager’s fight,” added the 67-year-old.
“I want my team to turn up and play with a stronger performance than on Sunday [against Tottenham], to respond well.”
Asked if he could one day imagine the relationship improving, as it eventually did with Alex Ferguson, Wenger replied: “I try to respect everybody. I think it’s important that I focus on my own team and forget all the rest.
“I am open always in life to everything, for peace. But what is important when you are a competitor is you give everything to win the next game.”
It was also suggested Arsenal, when Wenger finally walks away, could suffer a similar decline to that experienced at Old Trafford following Ferguson’s retirement in 2013.
“It can as well go better when I leave one day,” he joked.
“When you are such a long time at one club, like Ferguson was… it’s a bit like having children, even when you are not there anymore, you want them to be happy.
“I’m not in a position to judge what happened to Man United, I’m sure they will come back and fight for the Premiership again. They have the quality and resources to come back.”