The Blues confirmed fears that James would not make the trip. However, they disclosed it is due to an illness rather than injury.
The England international will join the team in America when he recovers.
James had an injury scare but is reportedly okay. The club will hope that he can stay fit this season after an injury-riddled 2022/23 campaign that saw him miss half of their games.
The 23-year-old is tipped to take on a leadership role at the club but must stay fit to make his mark. He faces competition from new signing Malo Gusto.
Fofana is out with a knee injury. The club are currently assessing the issue and did not place any timeline on his return.
He joined Chelsea last season in a deal worth around £69 million but has struggled with injuries.
The French international will hope to recover and join his teammates for pre-season training, which is crucial for conditioning.
Marcus Bettinelli, Benoit Badiashile and Armando Broja have also missed the trip to the US. They will stay behind at Cobham to continue their recovery.
Chelsea’s pre-season squad in full
Goalkeepers: Kepa Arrizabalaga, Gabriel Slonina, Lucas Bergstrom, Eddie Beach, Jamie Cumming.
Defenders: Thiago Silva, Trevoh Chalobah, Ben Chilwell, Marc Cucurella, Malo Gusto, Bashir Humphreys, Levi Colwill, Ian Maatsen, Alfie Gilchrist.
Midfielders: Enzo Fernandez, Conor Gallagher, Carney Chukwuemeka, Andrey Santos, Cesare Casadei, Lewis Hall.
Forwards: Mykhailo Mudryk, Raheem Sterling, Noni Madueke, Angelo Gabriel, Diego Moreira, Nicolas Jackson, Christopher Nkunku, Mason Burstow, Dujuan Richards.