Arsenal are in advanced negotiations to sign Valencia centre-back Shkodran Mustafi and are ready to pay a fee which could rise to £35m to get him, according to Sky sources.
The Gunners have been chasing the Germany international for weeks and have now increased their offer in the hope of getting a deal completed before the transfer deadline closes on August 31.
Sky sources reported earlier this month that Mustafi had agreed to the move, but the two clubs were unable to agree on the transfer fee.
Mustafi, 24, was on Everton's books as a youngster and played for Sampdoria before joining Valencia in August 2014.
Arsene Wenger has been forced to defend his transfer policy after his side failed to win either of their opening Premier League games against Liverpool and Leicester.
The Frenchman reassured frustrated fans that Arsenal were looking at a "number of players", adding negotiations were "ongoing" on Mustafi.
Despite signing 20-year-old Rob Holding from Bolton Wanderers, Arsenal are perilously thin at centre-half with club captain Per Mertesacker sidelined until the New Year and Brazilian Gabriel Paulista ruled out for six weeks.