Manager Arsene Wenger has admitted that Bolton Wanderers defender Gary Cahill would have been a welcome addition to the Arsenal squad.
The Gunners reportedly offered £6m for the 25-year-old during the recent transfer, which Bolton rejected.
Despite the initial interest from the London club, Wenger opted to sign Werder Bremen's Per Mertesacker.
When asked why he had chosen the German over the England international, Wenger said: "I don't want to compare. Personally, I like Cahill as a player.
"Both are good players. Mertesacker is a good player. He is more experienced. He has more international experience.
"Cahill is a young, promising English player. I suppose he would have done well for us."
Mertesacker could make his debut for the Gunners against Swansea City on Saturday.