Paul Merson has stated that Arsene Wenger must invest in a top-level defensive midfielder, following the injury to Francis Coquelin.

The pundit believes that Arsenal's title challenge will falter without the tough-tackling Frenchman, who has been ruled out for three months following an injury sustained during the Gunners' 2-1 defeat to West Bromwich Albion.

"I said weeks ago the one player Arsenal cannot afford to be without is Coquelin, and that was proved when they lost at West Brom. Mikel Arteta and Mathieu Flamini can't do it. They are nowhere near good enough any more," Merson told the Daily Star.

"Without Coquelin there is no one to win the ball back. Arsene Wenger has to buy a proper, top-class defensive midfielder in January or they can kiss the title goodbye.

"In previous seasons an injury to a player like Coquelin would have been the difference between Arsenal finishing in the top four or not. But this season it's the difference between them winning the title or not, because they have a chance this year."

Arsenal, who travel to Carrow Road to take on Norwich City on Sunday, are being linked with a move for Bayer Leverkusen midfielder Lars Bender.