There is at least some speculation that AS Monaco will want to have any deal done before it plays Auxerre on December 28th:
Bayern are waiting for an answer from Monaco regarding Nübel. The goalkeeper was still part of Monaco’s squad that faced Leeds in a friendly tonight. The return of Ligue 1 next week (Monaco to play Auxerre on 28 Dec) could be the deadline for a possible return to Bayern.
The negotiations are complicated. Monaco are in the race to qualify to the Champions League and are still in Europa League, so they’re unwilling to let their starting goalkeeper go mid-season without a proper replacement. In addition, Monaco actually wanted to sign Nübel permanently. The French club had contacted Bayern back in October, but Bayern made it clear Nübel was not for sale.
Bayern Munich is also reportedly in talks with Borussia Mönchengladbach’s Yann Sommer, who could also be a viable option for the Bavarians, but it is clear that there might not be much rest for sporting director Hasan “Brazzo” Salihamidžić.
“It’s important to find the best solution for our team in the short term. As far as the summer is concerned, we’ll manage that. We want to compete for all titles this season. We’re exploring different scenarios,” Salihamidžic said in an interview for Sport Bild (via @iMiaSanMia). “But of course Alexander Nübel would be an obvious solution. In the end, AS Monaco has the last say.”