The Argentine stepped up to the plate for the Gunners last season when injury ended Bernd Leno’s campaign early.
Martinez proved his worth with a string of outstanding displays for Mikel Arteta’s side, but has openly admitted he would only stay at the club if he was to remain No.1.
According to the Independent, the 28-year-old has been given no such promises over his role and after rejecting a new contract offer recently, the club have decided to move him on.
Aston Villa are expected to come in with a new bid, improving on their previous £15 million offer, with the Gunners valuing the stopper at £20m.
The report states that Martinez has already come to an agreement with the Midlands club on a four-year contract worth around £60,000 a week.
Bernd Leno is also set to reassume the No.1 role this Saturday for Arsenal’s Premier League opener away at Fulham.
Given the injury to Tom Heaton, Martinez would start the season as Villa’s first-choice stopper should he complete a move.
La Liga side Villarreal are also interested in acquiring the services of the goalkeeper, but he would prefer to remain in England’s top flight.
Despite the Atletico Madrid midfielder’s willingness to move to the Emirates, his £45m release clause is proving to be a sticking point.
The sale of Martinez could provide funds to put towards new signings, even though Mikel Arteta wanted the goalkeeper to stay and compete with Leno to be No.1.