Josh Acheampong's first senior goal sparked a second-half flurry, helping Chelsea to victory at the City Ground.
The Blues were outplayed in the first half but stunned Ange Postecoglou's struggling side with two quick goals after the break. Acheampong's 49th-minute header opened the scoring, before Pedro Neto doubled the lead.
Reece James added a third late on to make sure of the points and punish a Forest side that could have scored two or three goals themselves. Chelsea ended the match with 10 men after Malo Gusto was sent off late on.
Author's summary: Chelsea wins at Forest with a thumping score.