Arsenal have a few defensive issues to work out ahead of their trip to Watford on Saturday, with a number of absentees and doubts forcing manager Arsene Wenger into changes.

Arsenal had been enjoying the benefits of a settled back-line as the quintet of Laurent Koscielny, Shkodran Mustafi, Nacho Monreal, Hector Bellerin and Sead Kolasinac helped them keep four clean sheets from their last four league games.

However, news that Shkodran Mustafi will be out with a hamstring injury and persistent doubts over Laurent Koscielny’s fitness will force them into changes for their trip to Watford on Saturday.

Their absences could see Rob Holding and Per Mertesacker return to the starting line-up. Holding filled in ably for Koscielny against Brighton and seems to be the first-choice back-up at the club should one of the main three be unavailable. Mertesacker, meanwhile, remains a dependable player who should be able to cover for Koscielny in the short-term.

Arsenal’s visit to Red Star Belgrade may complicate issues a bit, however. Arsene Wenger has so far rotated his whole starting eleven for the Europa League games, but may have to play Holding and Mertesacker twice in the same week due to a lack of available options. While Holding shouldn’t have a problem playing multiple games, Mertesacker may struggle I feel.

In which case, much could depend on the fitness of Calum Chambers. The 22-year-old has been out with a hip injury that he picked up playing against Cologne, and it’s uncertain if he’ll be fit enough to take part in the game against Red Star. Should he not be fit in time, Wenger may opt to risk Koscielny against Watford so that Mertesacker could be fresh for the Europa League.

Another option is to return to using a back four, with Monreal partnering either Holding or Mertesacker in the middle. Wenger, though, seems to only make the switch when Arsenal are chasing a game, and would rather play someone out of position to ensure a back three can be maintained.

Whatever the scenario, Arsenal should be able to play actual defenders in their back-line against Watford. In emergencies, Arsenal can call upon Sead Kolasinac to move in-field and deploy Ainsley Maitland-Niles at left wing-back.

Maitland-Niles has also played centre-back during pre-season, along with midfield Mohamed Elneny. However, Arsenal’s current injury situation isn’t so bad that they’ll need to resort to such measures.