Arsene Wenger admits selling Kieran Gibbs to West Brom felt like losing a member of his own family.
England full-back Gibbs left Arsenal for the Hawthorns on the penultimate day of the transfer window.
He returns to the Emirates Stadium on Monday night as Tony Pulis' side take on the Gunners in the Premier League.
Gibbs came through the ranks at Arsenal before breaking into the first team at 18 and going on to represent the club 230 times in all competitions.