Aaron Ramsey
Aaron Ramsey asked to be substituted early in the second-half during Arsenal's 2-0 win over Bayern Munich in the Champions LeagueGetty

Arsenal have been dealt a major injury blow with Aaron Ramsey set to be ruled out for a month after suffering a hamstring injury during Arsenal's 2-0 win over Bayern Munich in the Champions League on Tuesday (20 October). The midfielder asked to be substituted midway through the second-half after pulling up while doing his defensive duties.

According to the Mirror, the north London club are still not sure as to the extent of the damage to the Welshman since the swelling in his leg prevented the doctors from taking any scans. This has prompted the Gunners medical staff to fear that the injury could be bad, which could rule out the former Cardiff City player for around four weeks.

The midfielder's injury will come as a big blow to Arsene Wenger ahead of crucial clashes in the Premier League and Champions League. The Frenchman has already ruled out the Welsh international for the clash against Everton on Saturday (24 October), but if the report is right, Ramsey could miss the return leg against Bayern Munich and the north London derby against Tottenham Hotspur on 4 November and 8 November respectively.

The 26-year-old midfielder has a history of hamstring injury troubles, after missing big chunks of last season with similar problems. The Gunners star missed close to three months of football in the 2014/15 campaign and will be hoping it is not a repeat of the same. He has established his place in the Arsenal starting XI albeit on the right-wing and played an important role in wins against Manchester United and Bayern Munich in recent weeks.

Ramsey will now join Tomas Rosicky, Jack Wilshere and Danny Welbeck, who are all long-term absentees and are only expected to return after Christmas. The Welshman, however, could return much earlier than the trio, who are yet to make an appearance for the 12-time FA Cup champions this campaign.