The Frenchman was forced from the field during the first half of the Champions League play-off in Istanbul after receiving a deep cut to his face following a challenge from Pierre Webo.
Carl Jenkinson came on and Bacary Sagna moved into the centre as Arsène Wenger shuffled his pack, and Mertesacker was pleased with the way the backline adjusted.
Unfortunately we've got a few injuries now but we have to stick together even morePer Mertesacker
"We tried to adapt," Mertesacker told Arsenal Player. "Carl Jenkinson came on for the second consecutive time. We're still alive.
"Laurent came back and he's alright so far. He's been to hospital and now we need a good recovery because on Saturday we're going to face Fulham away. That will be a massive game. We don't want to drop more points [in] the Premier League.
"I think we just have to stick together. That mental part is the most important part for us. Unfortunately we've got a few injuries now but we have to stick together even more, try to find our spirit back and tonight I think we did it well.
"We have to respond again on Saturday [to show] that we are a good team.
Mertesacker again captained the team in the absence of Thomas Vermaelen and Mikel Arteta, and the German is enjoying the role.
"It's nice," he said. "[This was] the first win this season so we'll just keep on going.
"It's an unusual situation for me. We have lots of players who take responsibility. It's not only me. We have a lot of players who are important for us.
"Unfortunately we lost Mikel and Thomas due to injury so everybody steps in. It's not only me."Copyright 2014 The Arsenal Football Club plc. Permission to use quotations from this article is granted subject to appropriate credit being given to www.arsenal.com as the source 22 Aug 2013