Deco injured a thigh in the warm-up and Carvalho suffered a knee injury early in the 1-1 draw at Stamford Bridge.
Scolari said: "The game is one of the best games we've played this season, because we have many problems.
"After we lost Deco, Manchester controlled the game for 15 minutes and they played better than us."
Scolari added: "They made a goal - and after this, we improved. We had more chances than them but we missed some chances in front of goal.
"At half-time I said we wanted Lampard and Ballack more up front, nearer the strikers - and we put Drogba on."
"I feel we have missed a good chance, obviously. If we had had a bit more energy, we would have been okay," he said. "We started to drop off the pace a bit in terms of the speed we were playing at.
"That was a bit of a disappointment because it allowed them to regroup at half-time.
"We started to give the ball away in the second half and that got them back into the game. They had a couple of chances, but that's about all they had."