Arsenal are trying to conclude a deadline-day deal for long-term target Thomas Partey from Atletico Madrid.
The Ghana midfielder, 27, has a release clause of £45m.
The Gunners' Uruguay midfielder Lucas Torreira, 24, is likely to move in the opposite direction and join the La Liga side on loan.
Partey, who joined Atletico in 2011, made 35 league appearances and scored three goals for Diego Simeone's side as they finished third last season.
Arsenal have been linked with Partey and Lyon midfielder Houssem Aouar, 22, throughout the summer transfer window.
However, Aouar has told French TV he will remain at the Ligue 1 club.