Mateo Kovacic has joined Chelsea's growing injury list after missing training along with Kepa Arrizabalaga and Kalidou Koulibaly.
The trio are now expected to miss Chelsea's upcoming Champions League match against Dinamo Zagreb at Stamford Bridge.
Kovacic is managing an ongoing knee issue and Kepa was substituted at half-time with a foot injury during Chelsea's 4-1 away defeat to Brighton at the weekend.
Koulibaly has been out with a knee issue of his own but is expected to be in contention for the remaining fixtures before the World Cup; against Arsenal, Manchester City and Newcastle.
Carney Chukwuemeka also trained alone during manager Graham Potter's last training session ahead of the Group E finale.
With N'Golo Kante, Reece James and Wesley Fofana injured long-term, the Blues called upon several academy players to fill in the gaps for the session.
Lewis Hall, Zak Sturge, Eddie Beach and Dion Rankine crossed the road at Cobham from the academy building into first-team training.
However, Sturge is thought to be ineligible to play in the upcoming match, which may see possible bench roles for the other three.
Juventus loanee Denis Zakaria is widely expected to make his debut but could be withheld so he can leave the club in January.
FIFA rules limit players from lining up for more than two clubs in a single season.
