Chelsea made it 10 wins in a row with victory over Sunderland but Antonio Conte admits his side were made to fight hard for the three points.
Sunderland contained the threat of the Chelsea attack for the bulk of the first half, with Jordan Pickford rarely tested in the Black Cats goal.
Sunderland had a good chance to draw and only a great save by Thibaut allowed us to win.
David Moyes’ side almost made it to the break intact but Cesc Fabregas popped up with a low finish five minutes before half-time, his strike proving the winner.
It was a far more open second half, with Chelsea dominating the possession but it took a superb late save from Thibaut Courtois to deny Patrick van Aanholt an equaliser.
A delighted Conte reflected: “I am pleased, for sure, because it’s fantastic to win 10 games in a row in this league because this league is very tough.
“It’s very tough in every game, you have to fight until the end to take three points.
“This game is an example. We had to fight a lot to win this game.
“We created many chances to score the second goal and to kill the game.
“Instead, we didn’t kill it and at the end, Sunderland had a good chance to draw and only a great save by Thibaut allowed us to win.
“But I am pleased because, I repeat, to win 10 games in a row in this league is not easy.
“I am pleased for my players because they deserve this for their commitment and work-rate every day, in every training session, during the game.”
Chelsea took the lead through Fabregas’s 40th minute strike, the midfielder playing a one-two with Willian before curling a low effort past Pickford.
Conte added: “I am very happy for him because Cesc is a great example for the other players.
“This is only the third game he has started, but this month, he has had a fantastic period, great commitment.”
Chelsea are now six points clear at the summit of the Premier League, with Sunderland bottom and four points adrift of safety.
Conte added: “I prefer not to look at the table, I prefer this for me, for my players because we are doing something important until now, but the league didn’t finish today.
“We are on top of the table, but there are still three games to end the first part of the season and then 19 games.
“This league is very tough and I think until the end, it will be a big battle between six teams.”