Arsenal have welcomed full-back pair Hector Bellerin and Kieran Tierney back to training after lengthy spells on the sidelines, although neither is expected to face Watford this weekend as they each now work on building up their fitness.

Bellerin has been out of action since January as a result of a serious knee ligament injury, while Tierney underwent a double hernia operation at the end of last season and is yet to play for the Gunners since his £25m summer transfer from Celtic.

In time, both, who 24 and 22 years of age respectively, are expected to be Arsenal’s starting full-backs for the long-term future.

For Tierney in particular, his return to training on Thursday was a boost as he was previously not expected to be back with the rest of the squad until October.

Arsenal have already used two different left-backs so far this season, with Nacho Monreal starting each of the first three games of the new campaign. The Spaniard even wore the captain’s armband for two of the outings, but left to join Real Sociedad at the end of August.

Bosnian international Sead Kolasinac was given the nod in the recent north London derby, which was Arsenal’s last game before domestic football was put on pause.

Versatile home-grown talent Ainsley Maitland-Niles has been filling in at right-back in Bellerin’s absence, while the equally versatile Calum Chambers has been back in the fold and on the bench this season after coming back from a loan at Fulham.

Arsenal were given another defensive boost earlier this week when Rob Holding, another long-term injury absentee, returned to full training. The 23-year-old has played two games with the Under-23 team this season, but hasn’t been seen in first-team action since December.