Steve Coppell felt Reading paid the price for missing chances as they surrendered a lead against Chelsea.
Andre Bikey's tap-in on the half hour gave the home side a half-time lead at The Madejski Stadium.
However, the game changed at the start of the second half as Chelsea scored twice in a three-minute period to take all three points.
Coppell felt the double strike so soon after the break sucked the life out of the hosts, who then saw debutant Kalifa Cisse sent off in the 72nd minute.
"I am disappointed but maybe I would be more critical of our finishing in the first 45 minutes," he said.
"When we were 1-0 up we had some really good opportunities to be more in front.
"We knew they would make changes at half-time given the quality of their
players. We knew the changes would ask different questions of us.
"They played with a lot more depth in the second half and that allowed Frank Lampard to push on for the first goal which was a bad one from our point of view in lots of ways.
"But their second goal from Drogba was great finish. When you go down 2-1 so quickly in the second half all the energy at half-time evaporates."
On Cisse's second yellow card, Coppell felt Claudio Pizarro made a meal out of the midfielder's challenge.
"By the reaction of the player you would think there had been heavy contact. He laddered his sock so it must have been a bad injury," he added.
"But when you've been booked in the first half then you are always treading a
dangerous line. It's an expensive lesson he's learned."