Arsenal midfielder Matteo Guendouzi, who is on loan at Hertha Berlin, has tested positive for coronavirus.
The 21-year-old tested positive on two occasions on his return from international duty with France U21 and will now self-isolate for 10 days in Germany.
Guendouzi is reported to be asymptomatic and feeling well.
The Frenchman had no contact with any other Hertha Berlin players on his return, according to the club.
He was set to be presented to the media on Thursday afternoon and in line to make his debut in the Bundesliga fixture with Stuttgart on Saturday following his Deadline Day loan move from Arsenal.
Hertha Berlin said Guendouzi returned two positive tests on his return on Tuesday morning and Wednesday evening.
He had captained France U21 to victories over Liechtenstein and Slovakia in his first matches since last month's international break.
The midfielder had been surplus to requirements at Arsenal since their 2-1 defeat to Brighton on June 20, where he was involved in a post-match altercation with Neal Maupay.
Thomas Partey says Mikel Arteta's "exciting" plans helped him decide to join Arsenal.
The new signing arrived at the Gunners' training ground for the first time on Tuesday after international duty and could make his debut against Manchester City this weekend.
The Ghana midfielder completed a £45m move from Atletico Madrid on Deadline Day and admits he must adapt quickly to the rigours of the Premier League.
"Arteta was very important [for the move]," he said. "Him and (technical director) Edu told me about their plans and it was so exciting, so I had to accept it.
"It's a great challenge. I want to experience new challenges. I'm ready to give it my all and help the club get back to where it belongs."
Former Arsenal striker Nicklas Bendtner has admitted to having regrets over his career and says he "became too fond of the lifestyle that came with the money" of being a professional footballer.
The ex-Denmark international recently released an autobiography in which he claims to be "completely honest" about his past difficulties.
Bendtner was signed for Arsenal by Arsene Wenger as a youth but struggled to realise his potential and - in his new book - he admits to drinking and gambling during his time at the Gunners.
"I became too fond of the lifestyle that came with the money," he said, and quoted by the Guardian.
"I want to go back in time and hit that young lad on the head with a hammer. Make him understand what a chance it is. That he has something special - something he has to look after."