Vermaelen key as Arsenal battle Liverpool for Ajax defender Vertonghen
Wenger missed out on Vertonghen, 24, in summer because the Dutch giants wanted him to boost their Champions League chances.
But they are resigned to losing him and may sell in the January transfer window.
Kop boss Kenny Dalglish is an admirer but Wenger is favourite to land his man.
"We know he's leaving but not when - maybe in January."