Arsene Wenger's transfer plans are threatening to be derailed after Arsenal defender Laurent Koscielny suffered suspected skull damage during the Champions League play-off first leg against Fenerbache in Istanbul.
Goals from Kieran Gibbs, Aaron Ramsey and Olivieir Giroud helped The Gunners put one foot in the Champions League group phase but the game was overshadowed by injury to Koscielny who was replaced by Carl Jenkinson after just 33 minutes in the Turkish capital after receiving a kick from Fenerbache forward Pierre Webo.
With Thomas Vermaelen out with a back problem and Ignasi Miquel on loan at Leicester City, Per Mertesacker is Arsenal's only recognised full-fit centre-back with Bacary Sagna employed to partner the German for much of the 3-0 win on Wednesday.
Koscielny is suspended for the Premier League trip to Fulham on Saturday after his dismissal on the opening weekend against Aston Villa but if he has suffered substantial skull damage the French defender could be forced to spend an extended spell on the side-lines.
"Laurent Kosielny's [injury] has opened very deeply the skull and we had to take him to hospital," Wenger said.
"I was not happy with the kick because I feel always that you can ease a bit off. Only the player in the end will know what he did.
"We are concerned because we had to send him to hospital to see if he has not broken a bone. We are waiting for him to come back now.
"We are waiting for information to find out if he can fly home with us. We faced a lot of challenges on Saturday and tonight again.
"That is part of the intensity of the game. Today, of course, there was so much at stake you can understand that.
"This special challenge, I don't know really what to think about it. When I saw it, I was angry. But I don't know if the player can explain to you exactly what he did."
With only Mertesacker in reserve, Wenger could be forced to revaluate his transfer targets during the remaining 10 days of the summer window. Despite failed attempts to sign Stevan Jovetic, Gonzalo Higuain and Luis Suarez, Wenger's number one priority in the window has seemingly been a striker to lead the Arsenal attack.
Injury to Koscielny could force Wenger into turning his attention away from adding an attacking player to the squad - particularly due to the early season form of Giroud who netted his second goal in as many games this season against Fenerbache.
Arsenal have been heavily linked with a move for Swansea City's Ashley Williams, who has been handed the club captaincy in order to keep him at the Liberty Stadium but chairman Hew Jenkins says the Wales skipper is not for sale.