Franck Leboeuf, whose penalty did for Leicester City's Wembley dream, scored again but was later dismissed for handling on the line. Their player- manager, Ruud Gullit, suffered suspected ankle ligament damage after replacing the ineffective Gianluca Vialli, while Eddie Newton's thigh did not even get through the pre-match warm-up.
"Things weren't too good before the match but are now considerably worse," Graham Rix, the Chelsea assistant manager, said. "We have got a busy programme ahead and, despite everybody saying that we have got a big squad, we are now down to the bare bones."
It would have been an injustice had County not won. Chelsea's goals from Scott Minto and Leboeuf came from their only shots on target and they were forced to defend desperately for long periods.
Only the stand-in goalkeeper Frode Grodas, again deputising for Kevin Hitchcock, kept Chelsea in the picture for so long and he had no chance with Ashley Ward's two goals and a penalty from the inspirational playmaker, Aljosa Asanovic.
Ward's delight at boosting County's hopes of avoiding relegation was tempered by the fact that his partnership with Dean Sturridge faces another break-up.
The pair have scored seven goals in the last four games, but Sturridge is suspended for the next two matches, including next Saturday's FA Cup quarter-final with Middlesbrough.
"It always seems that I am saying how glad we are to be back and then one of us gets injured or something else happens," said Ward, whose injury- time winner came via a Sturridge mis-hit. "It has been that sort of season from day one."
Goals: Minto (16) 0-1; Ward (51) 1-1; Leboeuf (54) 1-2; Asanovic pen (62) 2-2; Ward (90) 3-2.
Derby County: Hoult; Carsley, Rowett, Laursen, D Powell, Stimac, Van der Laan, Asanovic, Dailly, Ward, Sturridge. Substitutes not used: Willems, Simpson, Flynn, McGrath, Taylor (gk).
Chelsea: Grodas; Leboeuf, Clarke, Myers, Vialli (Gullit 62; Nicholls 79), M Hughes, Wise, Di Matteo, Minto, Sinclair, P Hughes (Morris 76). Substitutes not used: Zola, Colgan (gk).
Bookings: Derby Stimac. Chelsea Minto, Di Matteo.
Sending off: Chelsea Leboeuf.
Referee: A Wilkie (Chester-le-Street).
Man of the match: Asanovic.
Attendance: 18,039.Reuse content