Arsenal are set to sign Brazilian international left-back Andre Santos from Fenerbahce for £6.2m.
The 28-year-old from Sao Paulo was bought by the Turkish club in 2009 from Corinthians in his homeland.
After Sunday's 8-2 defeat by Manchester United, manager Arsene Wenger said he was chasing new players before the transfer window closes on 31 August.
Wenger is also on the verge of signing striker Park Chu-young from Monaco.
Last season Santos made 25 league appearances for Fenerbahce, scoring five goals.
Santos played for Brazil as they won the Fifa Confederations Cup in 2009, but he did not make the 23-man squad for the 2010 World Cup Finals. He did return to play in the 2011 Copa America, but missed a penalty as Brazil lost to Paraguay on spot-kicks in the quarter-finals.
Having seen left-back Gael Clichy join Manchester City, Wenger played 21-year-old Kieran Gibbs in that position on the opening day of the season against Newcastle United.
Gibbs then injured his hamstring in the Champions League qualifying play-off first leg against Udinese.
Wenger used Bacary Sagna at left-back during the 2-0 Premier League defeat to Liverpool on 20 August, and the second leg against Udinese, where Arsenal qualified for the Champions League group stage.
But Sagna was ruled out at Old Trafford on Sunday, paving the way for another left-back, Armand Traore, to play, but he is now on the verge of leaving the Gunners for Queens Park Rangers.