Arsenal are closely monitoring the highly-rated Athletic Bilbao defender Unai Nunez ahead of the January transfer window, Football Insider understands.

The north London outfit are assessing potential centre-back options as the club look to strengthen their brittle defence.

An Arsenal source has told Football Insider that the Gunners have already jetted out on regular transfer missions to assess 22-year-old  Unai and plan to step up their rumoured pursuit.

The Premier League giants have been encouraged by the centre-half losing his regular starting role at the Spanish club.

Nunez started the first two matches of the season, playing the full 90 minutes of the 1-0 win against Barcelona in August, but he has found himself mainly playing a back-up role in the team following the return to fitness of first-choice Inigo Martinez.

That could open the window for the Gunners to make a swoop for a player who has been likened to Manchester City’s star Aymeric Laporte.

However, there is also interest in UNai from Everton, who have also struggled defensively in the new season.

Arsenal’s first-choice centre-back pairing this campaign have been Sokratis and surprise summer acquisition, David Luiz.

However, they have looked vulnerable and the Englishman Rob Holding is expected to challenge for a first-team role now he is fully recovered from a knee injury that has sidelined him for 10 months.

The Gunners spent a club-record £72million on Nicolas Pepe in the summer as well as £6 million for Gabriel Martinelli, £25 million for Kieran Tierney, £8 million for Luiz and £27 million on William Saliba.