Assistant manager Ray Wilkins claimed Chelsea were given a tough workout by QPR before overcoming the Championship side 1-0 in the third round of the Carling Cup.
A strike by Salomon Kalou on 52 minutes was the difference between these west London rivals on a night where Chelsea made 10 changes to the side which started their last Premier League game.
First-team stars Frank Lampard, Ashley Cole and John Terry all came off the bench as the Blues looked to close out the game.
"It's not a bad substitution to make," said Wilkins. "It's a testament to QPR that we had to use Frank, Ashley and John.
"QPR equipped themselves very well and gave us a very tough evening."
Joe Cole made his first appearance since damaging knee ligaments eight months ago and the England midfielder was pleased with his comeback after setting up Kalou's winner.
"I'm back now and it's blinding," Cole said. "But I'm not going to get ahead of myself.
"There is going to be a lot of ups and downs. All I can do is keep working hard in training."