Laurent Koscielny
Laurent Koscielny's return to first-team action will give Arsene Wenger a big boost ahead of their crucial CL clash against Bayern MunichGetty

Arsenal have received a major boost on the injury front with the club optimistic regarding Laurent Koscielny's return from a hamstring injury for their key Champions League clash against Bayern Munich on 21 October. The French defender suffered a hamstring injury midway through the Gunners' clash against Olympiacos in their second group game in the elite European competition.

According to ESPN FC, the north London club's medical staff are quite confident of the defender's return to face the Bavarian giants after initial diagnosis ruled him out for at least three weeks. This will be welcome news for Arsene Wenger, especially since Arsenal's hopes of qualifying to the knockout phase of the competition are hanging by a thread following consecutive losses in their opening two group stage games.

Koscielny missed Arsenal's 3-0 win over Manchester United prior to the international break with Per Mertesacker and Gabriel impressing with an assured performance, but the French manager, who confirmed the injury, will be keen to have his compatriot back for the crucial clash against the Bundesliga champions.

"Laurent Koscielny will certainly be out, he has a hamstring strain and it looks like it will be three weeks, something like that," Wenger confirmed ahead of the game against United, as quoted on Arsenal's official site.

The report claims that the French international defender will not be risked for the clash against Watford in the Premier League following the international break, as the game against Bayern will make or break the 12-time FA Cup winners' Champions League dream this season.

Meanwhile, according to the Daily Mail, Mikel Arteta and Mathieu Flamini, who were both out with a hamstring injury and a dead leg respectively, are expected to return for the clash against Watford on 17 October.

The French midfielder suffered an injury during the north London club's 5-2 win over Leicester City, while the Arsenal skipper also suffered a slight muscular problem in the same game. Their return to the first-team will provide Wenger with much needed options in midfield owing to the number of games coming up following the international break.