Chelsea boss Jose Mourinho was pleased his side topped Champions League Group A by beating Levski Sofia 2-0 but sounded a warning about the next round.
Mourinho is expecting a sterner test in the knockout stages
He said: "Levski played okay. They gave us a game, and it was good because I could play some players who didn't have a lot of minutes in their legs.
"We don't play Barcelona or any of the English teams next but we can play Real Madrid, Roma or Inter Milan.
"It'll be tough. But playing the second leg at home can be a little help."
Mourinho admitted that his side were not really tested by Levski, as they secured a comfortable 2-0 win.
He added: "I know football, I know players' mentality. I know when you just need to finish a job - and that was a perfect example.
"We knew we just needed three points to be top of the group and at half time we knew the score in Barcelona (2-0 ahead of Werder Bremen), so we knew that we just needed a point.
"We were 1-0 up and we have a big month ahead of us, so I think the players just controlled their emotions and the game.
"They didn't play to their maximum - and I didn't demand a lot.
"The game was quite easy and played in an easy way. It was almost like a friendly."