Chelsea substitute keeper Carlo Cudicini was stretchered off in a neck brace as the champions beat Reading.
Cudicini, who replaced Petr Cech who was also stretchered off after 20 seconds, was left unconscious after a collision with Ibrahima Sonko.
Chelsea bagged the points after Frank Lampard's free-kick cannoned in off Reading defender Ivar Ingimarsson.
In a stormy second half Chelsea's Mikel Jon Obi and Reading substitute Andre Bikey were both sent off.
Chelsea suffered a blow after just 20 seconds when keeper Cech was caught on the head as he bravely plunged at Stephen Hunt's feet to save.
After a lengthy delay the Czech keeper was stretchered off and replaced by Cudicini.
The delay did not affect Reading who displayed an almost naïve lack of fear in carrying the game to Chelsea as they have to other Premiership opponents.
Reading had an escape 17 minutes in when Paulo Ferreira hared down the right and whipped in a cross which Ingimarsson headed against his own bar.
John Terry was harshly called for a foul on Kevin Doyle who folded like a card table under the England skipper's challenge but the Chelsea wall did its job as Nicky Shorey's free-kick deflected away for a corner.
Chelsea had a let-off when Hunt bullied and squirmed his way past defenders and into the danger zone where he squared the ball to Doyle who spun and cracked a shot against the inside of Cudicini's left-hand post.
Reading contributed to their own problems, with Hahnemann's mis-placed throw landing straight at the feet of Arjen Robben whose cross for Drogba allowed the American keeper to redeem himself with a sharp save at the foot of the post.
Reading's luck ran out, though, when they fell behind to an own goal.
Sonko's clumsy challenge on Lampard on the edge of the box earned him a booking and he was doubly punished as Lampard's free-kick pinged off him on the edge of the wall, and in pin-table fashion then ricocheted off Ingimarsson's boot into the net.
There was no lack of effort from Reading as they sought a route back into the game, but they needed to add wit and guile to their work to break Chelsea down.
But a moment of irresponsibility from Obi put his team under the cosh. Having been booked in the first half for clipping Lita from behind, he tugged Sonko back and was rightly shown a second yellow card to blot his full Premiership debut.
Chelsea showed why they relish situations where their backs are against the wall and Terry and Khalid Boulahrouz were towers of strength to keep Reading at distance.
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Reading's hopes took a nose-dive when substitute Andre Bikey showed his inexperience by pulling back Drogba to earn a second yellow card and even the dismissal count.
But the drama continued until the final whistle when Cudicini was left unconscious in a goalmouth collision with Sonko.
The Italian needed oxygen and lengthy treatment before being put in a neck brace and being stretchered off, with John Terry taking over in goal.
Reading manager Steve Coppell:
"Once they were down to 10 men in the second half we were in a good position but we couldn't get the goal and then we lost a player to a stupid red card.
"I couldn't ask for more but we must use our heads a bit better next time."
Read Chelsea boss Jose Mourinho's post-match quotes
Reading: Hahnemann, Murty (Bikey 36), Sonko, Ingimarsson, Shorey, Ki-Hyeon (Little 64), Sidwell, Harper, Hunt, Lita (Long 73), Doyle.
Subs Not Used: Stack, Gunnarsson.
Sent Off: Bikey (83).
Booked: Ingimarsson, Sonko, Bikey.
Chelsea: Cech (Cudicini 5), Paulo Ferreira, Terry, Boulahrouz, Bridge, Obi, Lampard, Essien, Robben (Kalou 82), Shevchenko (Joe Cole 63), Drogba.
Subs Not Used: Ricardo Carvalho, Wright-Phillips.
Sent Off: Obi (62).
Booked: Obi, Terry.
Goals: Ingimarsson 45 og.
Att: 24,025.
Ref: M Riley (W Yorkshire).