Chelsea boss Maurizio Sarri has ruled out Ruben Loftus-Cheek leaving the club on loan in the January transfer window.
The 22-year-old impressed for Crystal Palace last season, performances which earned him a place in England's World Cup squad.
After making four appearances in Russia a move back to Palace was blocked by the Blues - a suggestion he could be involved in the first team.
However, Loftus-Cheek is yet to make a Premier League start this term, with many of his outings restricted to the Carabao Cup and Europa League - which included a hat-trick aginst BATE Borisov.
But Sarri has high hopes for the Three Lions youngster and does not want to see him leave Stamford Bridge in the New Year.
“Ruben in October played four matches out of five," explained the Chelsea manager.
"I think at the moment the situation is not for a loan of course.
"He has improved, but he needs to improve more from the tactical point of view.
"The rest is good: he has great physical characteristics, he is fast, solid, he has impact, great characteristics.
"Technically he is very good and I think if he wants to play like a midfielder he has to improve in the defensive phase.
"But the potential is great."
Loftus-Cheek's sixth appearance of the season in the win over Derby coincided with Gary Cahill's return to the first team.
The 32-year-old has been on the periphery throughout the campaign - David Luiz and Antonio Rudiger have been preferred at centre-back in the Premier League.
Cahill admitted in September he might have to leave Chelsea in January, and Sarri says he will leave the decision up to the player.
"Cahill, it depends on him," he added. "He played very often in the last seven or eight matches.
"It depends on him and the club. He is very important on the pitch and out of the pitch.
"Cahill was the captain last season. I spoke with his team-mates and they all said he was a very good."