Arsenal have suffered an injury blow after Arsene Wenger confirmed star midfielder Aaron Ramsey is out of action for a month with a hamstring injury.

The Welsh international was substituted in the second half and was replaced by Alex Oxalde-Chamberlin during the Gunners’ 2-0 victory over Bayern Munich. The Frenchman also admitted there is growing concern over Alexis Sanchez’s fitness after the clash against the Bundesliga winners.

Ramsey underwent scans to find out the extent of the injury. The results were disappointing and Wenger has now revealed the midfielder will be on the sidelines and will miss Arsenal’s crucial clash in the coming weeks. The Gunners boss has blamed Wales’ international fixture for his injury.

“He [Ramsey] had a scan today but he’s out. I believe he will be out until after the next international break. With the [last] international break, the fact that he played against Andorra certainly cost Bale and him as well,” Wenger told the club’s official website.

Ramsey has expressed his disappointment just after his side sealed a crucial victory over Bayern in the Champions League clash.

“Fantastic result for us tonight, we worked so hard for it. Gutted to have to come off but was buzzing watching the lads at the end #AFC,” Ramsey tweeted.

Fantastic result for us tonight, we worked so hard for it. Gutted to have to come off but was buzzing watching the lads at the end #AFC

— Aaron Ramsey (@aaronramsey) October 20, 2015

David Ospina is also on the sidelines and Wenger believes the goalkeeper will not return to action until the next international break, which is in mid November. When asked about the South American, Arsenal manager said: David Ospina is out for our next game and certainly until the next international break.”

England international Jack Wilshere, midfielder Tomas Rosicky and former Manchester United forward Danny Welbeck have long been on the sidelines. Wenger claims the trio are expected to return to action during the start of the next year.

Arsenal host Everton in the Premier League clash at the Emirates this weekend. Ramsey and Ospina joins Wilshere, Rosicky and Welbeck in the list of injured players to miss the fixture against Roberto Martinez’s side.