Sami Khedira Toni Kroos
Sami Khedira has been struggling for game time at Real Madrid ever since Germany teammate Toni Kroos' arrival.Reuters

Former Arsenal striker John Hartson has urged Arsene Wenger to splash the cash on either Real Madrid midfielder Sami Khedira or Bayern Munich anchorman Javi Martinez, when the January transfer window opens.

The Gunners continue to struggle without an able senior holding midfielder in their ranks. Mikel Arteta and Mathieu Flamini have both struggled against teams which break with pace and against physical opponents, while Abou Diaby rarely leaves the treatment table.

Hartson wants Wenger to add some steel to his central midfield when the transfer window reopens in January, and has called on the manager to snap up either Khedira or Martinez.

"I feel teams get at Arsenal too easily at the back. Chelsea have two commanding central defenders but Arsenal have none. A defensive midfield player should offer protection. I like Mikel Arteta but he doesn't have the presence, while Abou Diaby can't string matches together. I see Calum Chambers eventually playing there but the summer buy from Southampton is needed elsewhere just now," the 39-year-old told Goal.

"Real Madrid's Sami Khedira has been linked and, although it would cost them £40 million to get his signature, Arsenal have the money and can't afford not to spend it. If they can't get him, Javi Martinez at Bayern Munich would fit the bill," Hartson added.

Khedira has been on Arsenal's radar for over a year now, with the speculations reaching the pinnacle last summer after it turned out the World Cup winner would not sign an extension to his contract with Real, which expires at the end of this season. However, the player eventually stayed on, after choosing to see off his contract.

The Gunners have also been linked with a move for Martinez since January. The 26-year-old had struggled for game time at Bayern under compatriot Pep Guardiola last season, managing just 18 Bundesliga appearances. The player has been sidelined with an anterior cruciate ligament injury since the start of the season but is now closing in on a return to the squad.