Fikayo Tomori has signed a contract extension until 2021 and will continue his development on loan at Derby County.
The 20-year-old defender moves to Pride Park for the 2018/19 campaign where he will work under the guidance of Frank Lampard, having featured regularly for another Championship side, Hull City, last season.
Tomori has been at Chelsea since Under-8 level and made his senior debut on the final day of the 2015/16 campaign. The following year, he was a mainstay of the England side that won the Under-20 World Cup.
Tomori joins fellow Chelsea loanee Mason Mount at Derby. They started their season with a 2-1 win at Reading in which Mount scored.