Arsene Wenger revealed 'congestion' at the centre of the Arsenal defence prompted his decision to allow Philippe Senderos to join AC Milan on loan.
The 23-year-old Switzerland international was today undergoing a medical with the Serie A club.
Senderos joined Arsenal from Servette in 2003, but has found himself slip down the pecking order at the Emirates Stadium.
Wenger feels he now has plenty of cover following the arrival of versatile former Manchester United defender Mikael Silvestre.
'Senderos has gone to Milan today and will complete a medical,' said Wenger, whose side take on Steve McClaren's FC Twente in the second leg of their Champions League qualifier tomorrow night.
'At the moment, he does not get the games here, and so now he can play somewhere and remains in a top-level club.
'We have [Johan] Djourou, we have Kolo [Toure], we have Senderos, we have [Alex] Song, [William] Gallas and [Mikael] Silvestre now who can play centre-back so we have a congestion there.
'We want him to play without losing him.'
Senderos' former Gunners team-mate Mathieu Flamini moved to the San Siro at the start of the summer.
Details of the deal for Senderos remain undetermined, with Wenger confirming: 'It has not been decided yet whether the transfer will be permanent.'