Chelsea winger Mykhailo Mudryk had to be substituted at halftime during the 0-0 draw against Fulham on Friday evening due to illness.
The Ukrainian international is, though, expected to be available for selection when the Blues take on West Ham this weekend.
Wesley Fofana has stepped up his comeback from a knee injury, and there is a chance that he could be named in the squad for the trip to the London Stadium.
However, Mateo Kovacic has taken longer than expected to regain fitness after a calf issue and he remains a doubt for the Hammers clash, while Denis Zakaria may need another 10 days to two weeks to recover from a thigh problem.
Christian Pulisic has posted on Instagram that he will be “back soon”, although the initial estimates made when he picked up his knee injury last month suggested he’d be out until mid-March.
N’Golo Kante (hamstring) is on course to return to full training by the end of February, but comeback dates for Edouard Mendy (broken finger) and Armando Broja (knee) have not been given.