Olivier Giroud said leaving Arsenal was the "toughest choice" of his career as he prepares to make his Emirates Stadium comeback, aged 40.
Giroud scored 105 times in 235 appearances across nearly six years for Arsene Wenger's Gunners before leaving to join Chelsea ahead of the 2018 World Cup.
The former France international departed Stamford Bridge for AC Milan before a one-year stint in Major League Soccer for Los Angeles FC.
However, Giroud returned to his homeland last year and the striker is set to face his one-time employers when Lille face Arsenal in north London on Tuesday night.
"Arsenal was a major part of my career and I had to leave in order to play at the 2018 World Cup," Giroud said.
"I was really sad when I left the club but I had to make that choice, and it was one of the toughest ones in my career, but it was important and necessary for the rest of my career.
"So, it is great to come back at 40 years old with a French club and to play against Mikel Arteta's Arsenal. That is a blessing. It is something I wanted to happen, and I feel very lucky."
Giroud was a three-time FA Cup winner at Arsenal but failed to land the Premier League during his time with the club.
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He played alongside Arteta and said the 44-year-old Spaniard, who has recently signed a new contract to remain at the Emirates until 2030, was always destined for management.
Arteta last season led the Gunners to their first league title in 22 years.
Giroud continued: "Mikel is a great person, a great manager and he has shown that with the team he has built.
"The Premier League title proves he has done incredible work, and he was given the time which was very important.
"I remember Mikel as a player, and you could see he was made for a managerial career because he was a leader on the pitch, but off it, too. He was very demanding with himself, and his team-mates and great technically.
"I really enjoyed my time with him. We won a few trophies together and it is a blessing to come back here and play against his team."