Mason Mount has apologised to Chelsea bosses for playing football in public when he was meant to be self-isolating due to the coronavirus outbreak, the PA news agency understands.
The England midfielder was spotted with West Ham star and best friend Declan Rice at a football centre near Barnet on Sunday.
Chelsea's players have been following government guidelines to self-isolate after Callum Hudson-Odoi tested positive for coronavirus last week.
The Blues' Cobham training ground will remain closed while the squad and staff are in self-isolation, with training potentially resuming in the week beginning March 23.
Mount is understood to have been reminded of his responsibilities by Chelsea, but the 21-year-old has also spoken to Chelsea chiefs himself by phone to make an apology.
Chelsea's players have been posting on social media of their efforts to keep fit while stuck at home, while club bosses have carried out a deep clean of their Surrey training centre.
The Premier League is currently suspended until April 4 due to the coronavirus pandemic.
Rice was not under the same restrictions from West Ham as his England team-mate Mount.
