The Blues captain has been given his first start since November 11, and his first under new manager Rafa Benitez, after coming off the bench in their 4-0 win over Stoke
Ross Turnbull is given another run out in cup competitions, with Petr Cech not included in the squad, while Fernando Torres is preferred over Demba Ba in attack.
Yossi Benayoun is also given a rare place in the Blues squad, while Marko Marin and Ryan Bertrand are preferred to Juan Mata and the suspended Eden Hazard on the wings.
Brentford include Clayton Donaldson in their starting team, after he scored a late winner in a 2-1 victory over Southend in the third round.
Brentford: Moore; Logan, Dean, Craig, Hodson; Douglas, Diagouraga; Donaldson, Forshaw, Forrester; Trotta.
Subs: Lee, Barron, Saunders, Adeyemi, Dallas, Reeves, Hayes.
Chelsea: Turnbull; Ivanovic, Cahill, Terry, Cole; Ramires, Lampard; Marin, Oscar, Bertrand; Torres.
Subs: Hilario, Ferreira, Azpilicueta, Mata, Benayoun, Ba, Ake.