As first reported by Goal's Charles Watts, the Gunners have indicated to La Liga - who hold the player's registration - that they will pay his release clause as they look to complete the deal before the 11pm deadline.
A legal team is at the club's London Colney training ground trying to wrap up the transfer.
Paying the release clause will speed up the transfer as no negotiations with Atleti will be required, and while a medical still needs to be completed, personal terms should not be an issue with Partey keen to join Arsenal.
Discussions with Atletico have taken place during the past few months, with the Gunners hoping to land the midfielder for a fee less than his release clause, but the Spanish side have consistently stated that the only way Partey will be leaving this summer is if that clause is activated.
Speaking after Sunday's win over Sheffield United, Arsenal boss Mikel Arteta reassured fans that the club would be doing all they can to add to the squad before Monday night’s deadline.
“What I can guarantee is that we are doing our maximum for that to happen, whether we are going to achieve it or not, I don’t know,” said the Spaniard.
“I cannot discuss the players that we want but we recognise certain positions that we believe we are short in. First of all in numbers and then adding different qualities to complement each other and this is what we are trying to do.
“I always try to be really honest and clear. Believe me that the ownership, the board, myself, are doing everything we can to maximise the resources we have to improve the team and to sustain and keep the players that are in this club to make this club successful.
“I have 100% backing from them. It's not just words, it's reality. Whoever knows me, if it wasn't like that I wouldn't say it but I say it because I feel it and it's true.”
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