Arsene Wenger says he will have "no problem" deploying a back four when Arsenal host Liverpool at the Emirates on Friday (22 December).

The Gunners have operated in a 3-4-2-1 formation for much of 2017 but Wenger opted to shake up his system for the first time this season against West Ham United on 13 December, naming a flat-back four of Hector Bellerin, Laurent Koscielny, Nacho Monreal and Ainsley Maitland-Miles.

He named the same back four for the weekend victory over Newcastle United, resting them midweek but keeping the same system in place for another meeting against the Hammers in the Carabao Cup on Tuesday [19 December].

Arsenal have not conceded a goal in the three matches in which Wenger has switched to a more conventional backline and while he has faith in the system, he has not ruled out switching to a back three when Jurgen Klopp's side come to town.

"I have no problem with [playing a back four]," Wenger said. "Overall I think that let's touch wood and focus on everybody defending well, then play with four or five."

Wenger's decision whether to revert to three at the back could depend on whether Shkodran Mustafi is fit to play. The Germany international has not featured for the Gunners since limping out of the 3-1 defeat to Manchester United at the beginning of December but is available for Friday's clash in north London, with Arsenal eager to avenge a 4-0 defeat on Merseyside in August.

"[Mustafi] should be fit to be available for Friday night," Wenger said. "I haven't decided [the formation] yet, but the fact that we are adaptable now to both systems [means] it will be down to me to make the decision, do we play in a four, or in a three, or in a five?

"I have to analyse that well. And as well, you have to guess a little bit who will play [for Liverpool]. It's not always the same, it depends on their personnel. They have plenty of offensive players, and looking at them recently, they have changed their teams a lot. So it's difficult to guess. But for me the most important is that we turn up with a positive performance."

Arsene Wenger
Wenger says he would be happy selecting four at the back tonight but Mustafi's return could change that. Getty