Former Chelsea midfielder Frank Lampard has called upon the club's fans to shrug off their "downbeat mindset" and "get behind the team".

Gunners fan groups have been vocal with their displeasure over the club's handling of its affairs in recent weeks, following a transfer window that saw them fail to land a string of top targets and turn down a £70m approach for the soon-to-be-out-of-contract Alexis Sanchez.

The club are also playing in the Europa League this term, having missed out on the top four for the first time in 20 years last season, and a recent 4-0 drubbing at the hands of Liverpool only served to fuel fans' ire further.

"There is so much negativity around Arsenal, whether it's the fans ringing up radio stations or going to the game with a downbeat mindset," Lampard wrote in his column for the Evening Standard. "They can all have an opinion on the manager and the players, it's their right. But when they start playing, they really should get behind the team.

I'm sure they will, but sometimes it feels with Arsenal recently like it's 50-50 - that they're going to support but also half be there to protest. I think they need to get that out of their system because Arsenal are capable of doing well in the Premier League and in Europe this season.

"I'm not an Arsenal man and it's easy to speak from the outside. I understand the emotions involved. But at the same time time, Arsene Wenger has signed a new contract, the transfer window is shut and Arsenal have a very good squad. It's time to focus on what this side can do over the next few months."

Arsenal's first game in the Europa League sees them host German side Koln on Thursday evening.