The midfielder - who scored twice in Tuesday's 4-1 win over Galatasaray in the UEFA Champions League - is struggling with a hamstring issue and will not feature against Newcastle, with defensive pair Nacho Monreal (ankle) and Laurent Koscielny (calf) also ruled out.
While Kieran Gibbs and Mathieu Flamini are available, Wenger has made his disappointment clear.
"It's a shame because he was getting close to matching last season's form," the Frenchman told Friday's pre-match news conference.
Arsenal welcome Newcastle to the Emirates looking to get back on track domestically after a first-half horror show at the Britannia Stadium saw them go down 3-2 to Stoke City last weekend.
With Newcastle in fine form after ending Chelsea's unbeaten start to the campaign on Saturday, Wenger acknowledged the difficulties his side will likely face.
The Arsenal boss - who has been the subject of calls to quit by sections of the club's support - also dismissed suggestions there would be any repeat of the touchline spat with Alan Pardew that took place when the Newcastle manager was in charge at West Ham.
"They are doing well and are on a good run so it'll be a good challenge for us. Overall we are on a good trend," Wenger added.
"[Pardew and I] had a problem once but we sorted it out. He has done very well because he's gone through a difficult patch.
"Society wants to win the next game and it's a permanent tribunal for everyone. Pardew has done a great job this season.
"We are united for one target: to do well for the club we love and that's what we want to achieve."
