Guus Hiddink accused Chelsea of complacency after watching his team cling on to a 2-1 victory at Norwich City on Tuesday.
The reigning champions got off to a flying start at Carrow Road, Kenedy rifling in the fastest Premier League goal of the season after just 39 seconds.
Diego Costa doubled the visitors' lead in first-half stoppage time, despite appearing to be in an offside position when he ran through to score, before Norwich mounted a spirited second-half comeback.
Nathan Redmond's goal in the 68th minute gave them hope but Chelsea held on to extend their unbeaten run to 12 games.
"We didn't want to go into that battle but they forced us into it," Hiddink told Sky Sports.
"We were sloppy in the first half, we started very well but I think we could have finished it off earlier in the first half, we were complacent to finish it off.
"Then we went 2-0 but in the end they made our lives very difficult."
Hiddink said he had not seen a replay of Costa's goal, but was quick to underline the importance of Chelsea's strong recent run, after a third consecutive victory.
"It's important, everyone knows how we started in December, we were down almost in the relegation zone," he said.
"We had to get out as soon as possible and now it's a few games in a row that we are winning and that's encouraging."
"It was horrible by the end," added Gary Cahill. "The last 15 to 20 minutes was tough.
"But in first half we were in control. In the second, it was a totally different game. Credit to them. It feels good to dig in and grind out the result."