The 67-year-old has confirmed that he will leave Arsenal at the end of the current campaign following 22 seasons at the north London club.
Arsenal are in sixth place in the Premier League table and look unlikely to finish in the Champions League qualification spots for the second successive season.
Manchester United are in second place and will want to ensure Liverpool FC don’t have the chance to overhaul the Red Devils in the final weeks of the Premier League season.
Jose Mourinho’s side were comfortable 3-1 winners against Arsenal at The Emirates back in December despite Paul Pogba’s second-half sending off in the English capital.
Arsenal were held to a 1-1 draw with Atletico Madrid in the first leg of their Europa League semi-final at The Emirates on Thursday night.
Former Arsenal star Merson is backing the Gunners to lose to Manchester United on Sunday evening ahead of their return trip to Atletico Madrid next week.
“They have to go to Old Trafford on Sunday where they will probably get blown away,” Merson told Sky Sports. “Wenger will have to play the reserves.”
Arsenal haven’t won the Premier League title since 2003-04 and haven’t reached the Champions League quarter-finals since 2010.
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