Reece James and Mason Mount will not play again this season while Kai Havertz has been ruled out of the clash later today.
They join Kalidou Koulibaly and Armando Broja in the treatment room but interim boss Frank Lampard will still have around 27 players to choose from.
James injured his hamstring against Real Madrid, playing through the pain in a huge Champions League match but ultimately ending his season early.
Mount is having minor surgery on a painful pelvic bone injury that needs four weeks to recover, while Havertz has a minor knee issue.
Koulibaly came off with a hamstring problem in the first leg against Madrid a fortnight ago, while Broja is out with a long-term knee injury but the rest of the squad is in good shape.
Lampard previously admitted that his players were lacking in fitness and “capacity” but has had a full week to prepare for Brentford.
It is the first time that Lampard and his coaches have had a clear run having had games every three days since coming in to replace Graham Potter.
They have lost all four matches but did see their side compete well against Madrid last week. Chelsea played in a 3-5-2 formation with Conor Gallagher up front but could return to a back four here.
It’s tricky to second-guess Lampard at the moment as he has changed the system and personnel in almost every game. He has now, however, taken a look at much of his squad and must make his decisions based on the performances that he has seen.
Lampard will likely stick with Kepa Arrizbalaga in goal ahead of Edouard Mendy. He will potentially use a back four of Trevoh Chalobah, Thiago Silva, Wesley Fofana and Ben Chilwell.
Cesar Azpilicueta could compete against Chalobah for James’s spot at right-back. In midfield, Lampard could reward Gallagher for scoring in the 2-1 defeat by Brighton and play him alongside N’Golo Kante and Enzo Fernandez.
Pierre-Emerick Aubameyang remains available up front but Joao Felix is more likely to start, possibly in a front three alongside Mykhailo Mudryk and Raheem Sterling.
Chelsea predicted XI (4-3-3): Kepa; Chalobah, W Fofana, Thiago Silva, Chilwell; Kante, Enzo, Gallagher; Sterling, Joao Felix, Mudryk.
