Arsenal midfielder Emile Smith Rowe has had surgery on a groin injury and the club hope he will return to training in December.
The 22-year-old has made four brief substitute outings this season.
In the last of those, which was a defeat at Manchester United, he suffered "a significant setback".
"In recent months, Emile Smith Rowe has been experiencing discomfort in his groin, which has limited his training and match appearances," said Arsenal.
"Following a significant setback at our Premier League match against Manchester United at Old Trafford on 4 September, and after further specialist consultations and discussions with our medical team, Emile underwent surgery to repair a damaged tendon in his groin.
"This successful surgery took place in London in the past few days and Emile's rehabilitation program is already underway.
"We are hopeful that Emile will return to full training in December."
Newcastle have agreed a deal to sign 18-year-old Garang Kuol from Central Coast Mariners, with the Australian forward joining the club in January.
"It's unreal. As a young boy in Australia, the Premier League is the main thing that everyone watches but nobody actually thinks they'll reach those heights," said Kuol.
"To be one of those people, to be in the position I am, it's amazing."
Meanwhile, Newcastle reportedly paid an initial £300,000 before add-on clauses.
Kuol earned his first Australia cap last week becoming the youngest player to represent his country since former Leeds and Liverpool Harry Kewell in 1996.
Kuol, who only signed his first professional deal in June, has emerged as a late bolter for the Socceroos' Qatar 2022 squad after four goals in his seven substitute appearances for the Mariners.
He also impressed in a cameo in a post-season friendly against Barcelona, earning praise from opposition manager Xavi.
