Chelsea attacker Callum Hudson-Odoi reportedly aggravated his injured hamstring during a training session on Thursday.
The 19-year-old has missed his club's last five matches in all competitions due to a hamstring problem but was believed to be closing in on a return to action.
Sunday's clash with Everton had seemingly been identified as a potential comeback match for the England international, who has scored once in 17 Premier League appearances this season.
However, according to The Athletic, the attacker suffered a fresh setback during a training session on Thursday and is now set for a longer spell on the sidelines.
Hudson-Odoi was strongly linked with a move away from Frank Lampard's side before ultimately agreeing a new five-year contract in the latter stages of 2019.
Chelsea will face Everton and Aston Villa in their next two Premier League matches before travelling to Bayern Munich for the second leg of their last-16 Champions League clash on March 18.
