Arsenal boss Mikel Arteta says new signing Mikel Merino will be out for a “few weeks” after injuring his shoulder during his first training session with the club.

The Spaniard completed a £31.6m move to the Gunners from Real Sociedad on Tuesday.

Merino, Arsenal’s second signing of the summer following the arrival of Riccardo Calafiori from Bologna, trained with his new club for the first time on Thursday.

The 28-year-old collided with a team-mate, resulting in a “small fracture” that will keep him out for a “few weeks”.

“Yes very unfortunate. Yesterday he had a collision and he has got a shoulder injury, unfortunately. It looks like he is going to be out for a few weeks,” said Arteta.

“He was really excited and everything was looking really good. He landed on the floor and Gabi landed on top of him and it looks like he has a small fracture probably.

“We have to see. He was in so much pain, we have to wait to do some more tests.”

Arsenal have won both of their opening Premier League fixtures, beating Wolves and Aston Villa.

The Gunners host Brighton – one of the other three teams in the division with a 100% record so far this term – at the Emirates on Saturday.