Atletico Madrid have reportedly earmarked Carlos Vela as their main target to replace Diego Costa, pressuring Arsenal to decide whether they want their former player to return next season.
The Mexican left North London in summer 2011 for £2.5m after struggling for opportunities under Arsene Wenger – with the Gunners inserting a £3.2m clause which allowed them to bring the player back to North London.
Reports in Spain earlier last month claimed that Arsenal had told Real Sociedad they were set to activate that clause - either to have him back at the Emirates or to sell him on for a profit as his buy-back clause for other suitors is €30m (£24m).
Arsenal are yet to make an official move and according to Marca they cannot afford to delay, as Atletico are keen on his signing – while Barcelona and Real Madrid are also monitoring the situation.
Real Sociedad are aslo keen on keeping him but according to Spanish newspaper Marca the player recently informed his current club that it would be difficult to stay as he has already received an "irresistible" offer from Diego Simeone's side to replace Costa – who is going to sign for Chelsea.
Nevertheless, Arsenal lead the race as they have until 1 July to activate the £3.2m clause – and then decide whether they want to keep Vela at the Emirates or sell him on.
The 25-year-old striker was a sensation in La Liga last season, scoring 16 goals and grabbing 12 assists in 34 appearances - making him the fourth-highest assist provider in La Liga after Angel Di Maria, Koke and Cesc Fabregas.
Asked about his future recently he said: "It makes sense that Arsenal activate the clause now.
"A club that sees that a player is performing well for three years and has the chance of having him back for just an extra million... [Arsenal received £2.4m for the 50% of Vela's rights in 2012]. If Arsenal wouldn't pay that amount they wouldn't be very intelligent.
"Arsenal gave me the opportunity to come to Europe when I was 17. I didn't have as many opportunities as I expected and I had to try new options. If I have to return to London, I will try to make things in a different way so that happened in the past won't be repeated again."