Watford midfielder Nathaniel Chalobah will undergo surgery on a knee injury he suffered in training last week, the club have confirmed.
Chalobah completed a £5.5 million move from Chelsea in the summer and impressed in the opening matches of the new Premier League season.
However, Watford performance director Gavin Benjafield confirmed that the 22-year-old, called up to the senior England squad for the most recent World Cup qualifiers, now faced a spell on the sidelines.
"Whilst we can't put an exact timeline on his recovery, we are expecting to see him re-integrating into the squad well before the New Year,'' Benjafield told the club's official website.
Chalobah had started all five Premier League games under new head coach Marco Silva before the injury forced him to sit out Saturday's win at Swansea which saw the Hornets recover from their 6-0 home thrashing by Manchester City.
Watford would only confirm the midfielder was set to "soon undergo surgery," but must now plan without Chalobah for a run of matches which include the visit of Arsenal as well as trips to Chelsea and Everton.
Chalobah was part of the England squad which reached the semifinals of the 2017 European Under-21 Championships in Poland, where the Young Lions lost on penalties to eventual winners Germany.
Although the midfielder did not play in either of the 2018 World Cup qualifiers last month, it was expected Chalobah would again be called up by Gareth Southgate for the ties against Slovenia and Lithuania which should see England secure their place in Russia.