Leandro Trossard played for Belgium on Thursday amid reports that Besiktas have submitted a bid to sign him on a permanent basis.

Dogan Gundogdu reported for Turkish outlet Sozcu on Thursday that Besiktas had made an offer to Arsenal for Leandro Trossard.
The Gunners were reportedly yet to respond to the bid at the time of Gundogdu’s report, but the suggestion was that Arsenal were open to cashing in for around €22m (£19.1m).
The Turkish transfer window remains open, so if Arsenal choose to sell then they’re free to do so immediately. The issue is obviously that they can’t sign any replacements (other than free agents), with the English window already closed.

Reports of ongoing negotiations clearly weren’t enough to stop Trossard playing football on Thursday night, with the winger coming on as a substitute in Belgium’s 6-0 win over Liechtenstein.
Though Arsenal haven’t officially confirmed Trossard’s recent new contract, the player did refresh his terms with the club ahead of the start of the new season. The deal still expires in 2027, but Trossard received a pay rise.
The timing of the new contract was in part due to specific contract rules, with the Premier League only allowing a pay boost without a contract extension before the season gets underway. If Arsenal and Trossard had waited any longer, the new contract would have required an extension.

So it could be argued that Trossard’s new deal doesn’t actually tell us much about his future. If he stays, Arsenal are clearly happy for him to be earning a little bit more, and the player would obviously welcome the extra cash.
But signing the new contract in August was a necessity, rather than a sign that a departure was off the table before the window closed. If Arsenal and Besiktas can reach an agreement, a late transfer is still possible.