Jose Mourinho said Chelsea suffered from a Champions League hangover as it was forced to settle for a point at Sunderland.

The Premier League leader stretched its advantage at the top to seven points with Saturday's 0-0 draw at the Stadium of Light, a 20th game unbeaten to start the season.

Mourinho sent out an unchanged lineup less than four days after the 5-0 romp over German side Schalke guaranteed its place in the knockout stages of European soccer's top club competition.

But the Chelsea manager saw his side fade visibly in the final quarter of its first of eight games in a hectic 34-day period that will play a big part in shaping the destiny of its season.

He said Sunderland's greater preparation time played a significant role in the London club failing to add to its nine-match winning streak on Wearside.

"Sunderland's players will have watched our game on Tuesday at their homes and they will have gone to bed at 11 pm," said Mourinho.

"We arrived at home from our game at 5 am on Wednesday, and that's something I don't forget, so for this reason I praise my guys. They deserve their Christmas party, that's for sure.

"Sunderland had a full clear week to prepare for this match and to develop a strategy against us. Some people might like to criticize defensive teams but I don't because they did it very well against us and achieved their goal of a clean sheet.

"We're not happy with a point but we have to be mature enough to realize that in this league every match is difficult. I have no negative words for my players because they tried everything they could to win the game and in the end it was a fair result.

"There's no time to be complaining because we move on to another match on Wednesday where we'll try to get the points."

Chelsea's lead will be back down to at least six points when it returns to action at home to Tottenham due to second-place Southampton hosting third-place Manchester City on Sunday.

Mourinho is forced into at least one change as the Blues' top scorer, Diego Costa, will miss the visit by Spurs through suspension after earning a fifth booking for catching defender Wes Brown with a flailing arm in the second half.

The Chelsea manager refuted suggestions Costa, who has sniped 12 goals so far, was fortunate to avoid a red card after escaping censure for a studs-up lunge at Sunderland skipper John O'Shea in the first half.

"I'll play Loic Remy or Didier Drogba instead. They have an opportunity to play on Wednesday as Costa is suspended," said Mourinho.

Sunderland head coach Gus Poyet paid tribute to his side, which had late chances to win through substitute Jozy Altidore and ex-England midfielder Adam Johnson.

Sunderland climbed three points clear of the relegation zone thanks to an eighth draw of the season, its fourth in a row unbeaten.

It hosts Manchester City on Wednesday and the former Chelsea midfielder said: "We have to be pleased with a point. In terms of our display it was the best for a while. You can talk as long as you like but it's what happens out on the pitch that matters.

"We put in a great defensive display and Chelsea didn't have an easy chance all game, which is testament to the way we played."