Mosquera has just one year remaining on his contract, so the La Liga club would be willing to sell at the right price. Arsenal sporting director Andrea Berta is leading the charge and is expected to improve the bid "in the coming hours".
DID YOU KNOW?
Valencia are reported to have not made much of an effort to keep Mosquera themselves, with the defender not hearing from the club about a new offer. There is some suggestion that they are waiting for their new CEO, Ron Gourlay, to start in July before offering terms.
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WHAT NEXT FOR ARSENAL?
The Gunners will be keen to have Mosquera in the building ahead of pre-season beginning next week. They are visiting Singapore and Hong Kong as part of their preparations.