The frequently ill-disciplined Swiss midfielder, an expensive summer arrival from Borussia Monchengladbach who has thus far done precious little in English football to justify his £30m ($38.6m) price tag, sustained an ankle knock before being replaced in the 65th minute of a morale-sapping 2-0 North London derby defeat to Tottenham Hotspur and has only a "small chance" of featuring this weekend.
While Xhaka is set to miss the visit of Jose Mourinho's potentially weakened side to the Emirates Stadium, centre-back Shkodran Mustafi should play. The German international was forced to sit out the FA Cup semi-final victory over Manchester City in addition to league meetings against Middlesbrough, Leicester City and Tottenham due to a thigh problem sustained in a training session following a heavy defeat by Crystal Palace.
Long-term absentee Santi Cazorla remains sidelined for the remainder of the campaign and fellow Spaniard Lucas Perez, last seen during an emphatic defeat of non-League Lincoln City in March, has experienced a setback in the final stages of his recovery.
"Lucas Perez is back in training but I think he will miss the next two days, he got a little problem yesterday," Wenger was quoted as saying at a pre-match press conference by The Mirror. "We have still Xhaka who is out from the kick he got from the game and Mustafi is back in normal training."
Once an eagerly-anticipated showdown between perennial title rivals, the latest edition of Arsenal vs Manchester United is a battle between two teams currently occupying sixth and fifth place respectively in the top-flight. Currently six points adrift of fourth with a game in hand, the Gunners, now guaranteed to end the season below Tottenham for the first time since 1995, know that they simply must win in order to keep their hopes of another top-four finish alive.
"The goal for us is to have the chance to achieve our target," Wenger said. "There's no other choice, we have to beat them.
"I don't know what Manchester United will do. Only a top level performance will get us the win we want. The only advantage we can give ourselves is to focus on ourselves and not speculate on any weakness of Manchester United."
Asked whether his traditionally tempestuous relationship with United counterpart Mourinho has now calmed, the under-fire Frenchman added: "I am open always in life for everything, you know, for peace."