Nathaniel Chalobah has extended his loan stay with Championship Watford until the end of the season.
The 18 year old midfielder arrived at Vicarage Road in August and has been an integral part of the club's promotion push.
Hornets boss Gianfranco Zola told the club's official website: "It's great news for us. He has become an important player for us since he came to the club.
"His performances have been getting better and better so we are delighted that Chelsea have decided to leave him here.
"It is a huge boost because if we want to keep improving and chasing the teams in front of us we need to have good players and Nathaniel is one of them."