Arsenal manager Mikel Arteta says teenage attacking midfielder Ethan Nwaneri will be “out for a few weeks” with a muscular issue.

The 17-year-old came off at half-time in Saturday’s 1-1 draw at Brighton after scoring the game’s opening goal.

The England Under-19s international made his first Premier League start three days earlier, during the Gunners’ 3-1 win at Brentford.

“Unfortunately, he has picked up an injury and he is going to be out for a few weeks,” said Arteta on Monday.

Nwaneri made his first-team breakthrough this season, with Saturday’s goal his fifth in 18 appearances.

He has enjoyed more game time following a hamstring injury to Bukayo Saka, which will keep the influential England winger out for “many weeks”.

On Nwaneri’s injury, Arteta added: “He didn’t really know, to be fair. He said, ‘I am feeling something but I don’t really know what it is’.

“He has earned the right to step up and play for us and now he has started some games – some big games – and impacted those games in the way he has done, in different positions too.

“I am gutted for him because the injury is going to stop that, but it is another step in that development phase that he is in. I am really happy with the way he is going.”

Raheem Sterling was also injured days before Saka, and Arteta said the on-loan Chelsea forward will be back “hopefully very soon”.