Fernando Torres was taken off after 45 minutes as he extended his unwanted run to 20 games without a goal on Saturday.
Torres was hauled off at half-time after having just 15 touches of the ball in the first-half at Stamford Bridge as Chelsea were held 1-1 in their FA Cup 5th round match with Birmingham.
The Blues had trailed 1-0 at half-time, leading to Didier Droba - who replaced the £50million flop - holding an impromptu team talk in the tunnel before the second half.
Drogba helped inspire Chelsea's second-half equaliser, which was scored by Daniel Sturridge as the Premier League side were forced to settle for a replay at St Andrew's.
Torres' substitution suggests under-pressure manager Andre Villas-Boas has finally ran out of patience with the misfiring striker, with Drogba now possibly in line to start next week against Napoli in the Champions League.
Villas-Boas came in for stick from the Chelsea fans throughout the game, with chants of former manager Jose Mourinho ringing around the stadium.