Wenger also has concerns with defender Sead Kolasinac and Laurent Koscielny.
And the former Bournemouth and Bolton loanee is hopeful that run can start when the Premier League resumes this weekend, with north Londoners travelling to Watford, having returned to the best physical shape of his career.
"I don't think he will be available before the next global break".
"Kolasinac is a minor problem, a hip problem".
"Koscielny has a definite final test tomorrow".
Alexis Sanchez, who saw his 2018 World Cup dreams crushed when Chile lost to Brazil on Tuesday, will join the group on Friday and Wenger said he would assess the striker's fitness.
The Italian-owned side are seriously impressing this season, and will pose a tough task for our boys, despite our top form coming into the match.
Man Utd vs Liverpool is just another game, nothing to prove - Mourinho
Mata became an important figure for United, and that remains the case now that he is working with Mourinho again. Jose Mourinho has insisted that Marouane Fellaini's injury problem is not a blow to Manchester United .
"I will decide what I have to do when Koscielny has his test tomorrow".
He added: 'The player I expected to lose the least during the break was Mustafi.
'He didn't play in their first game and we lost him in the second - we have to cope with that now'.
Alexis Sanchez will not report back from worldwide duty with Chile until Friday, but Wenger has no concerns over the forward or Aaron Ramsey's mental state after their World Cup exits.
Our lack of defensive experience could well pose as a problem however, with Calum Chambers, Rob Holding, Nacho Monreal, Maitland-Niles, Sead Kolasinac and Mo Elneny our only available stars for the three central roles and left-sided wing-back role.
The summer transfer window was one the craziest we have ever seen.