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.
Partey, who won the 2017-18 Europa League and 2018 Super Cup with Atletico, signed a new deal at the Wanda Metropolitano in 2018, until the end of June 2023.
Among their completed deals, the Gunners have so far added Brazilian defender Gabriel Magalhaes for 26m euros (£23.14m) from Lille, former Chelsea forward Willian on a free transfer and re-signed Dani Ceballos on loan from Real Madrid.
The Premier League side's French midfielder Matteo Guendouzi, 21, has moved to Bundesliga side Hertha Berlin on loan, while Bosnia and Herzegovina defender Sead Kolasinac, 27, could potentially return to Germany via a loan move to Bayer Leverkusen.
'Arsenal have to take one last step'
Analysis by Spanish football expert Guillem Balague
There is no deal to be done with Atletico Madrid [for Partey] because Atletico will not negotiate at all.
That means what Arsenal have to do is go to La Liga and say they are willing to meet his buyout clause.
So no negotiating is taking place, Arsenal just have to take that last step.
It has been reported in Spain they they are willing to pay the 50m euros of his buyout clause, so we will have to see.
Partey is a midfielder with the ability to pass short and long with quality. He's very intelligent in the way he moves, brave in the way he presses high and helps the team with high dynamism.
One-touch football is something that he enjoys. He is strong, fast as well, so there is a lot to like with Partey.
'Partey signing would be a massive statement'
Analysis by former Premier League defender Micah Richards
Thomas Partey - what a signing. I cannot believe there are not more clubs lining up for him.
He is so good. A lot of people just think about him defensively, but he has actually got quite a bit going forward.
He has scored goals for the national team and a few for Atletico Madrid as well. If Arsenal can get him it would be a massive deal for them.
Arsenal are doing their business quietly but, if they are able to get Partey, it would be a massive statement.
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