West Ham boss Slaven Bilic has warned Chelsea that they cannot consider the Premier League title race to be over.
Antonio Conte's side hold a 10-point lead at the top of the table with 12 matches left to play, having won all but three of their last 17 top-flight games.
"I'm surprised how good they have been," Bilic told a news conference. "I was expecting him to have a strong impact because he had it at Juventus.
"I watched Juve quite a lot and I was studying his game. I didn't know because no-one knows.
"I expected him to do great long term and it is a surprise they are 10 points clear. Conte is a great manager, he done it at Juve, he done it with Italy. A brilliant manager, of course.
"It [the title race] is still very open. Many, many points. If they slip up, which you can in every game, other teams need to be ready."
Bilic said he is "optimistic" of having Carroll available and is delighted that he was not tempted by interest from the Chinese Super League during the transfer window.
The Big Man is back in training! prepares for the leaders March 1, 2017
"No way, no way, you know how much I rate him. He is one of our best players and we want to keep him," he said when asked about Carroll moving to China.
"Chinese clubs send their representatives over to investigate. They were watching other players but they fell in love with Andy. The club didn't try to sell him.
"Andy heard the speculation. Suppose he was flattered by it but we didn't talk about it at all."
Bilic's contract expires in 18 months' time but the former centre-back pointed to the shock sacking of Claudio Ranieri by Leicester City when asked if his own future was a concern.
"The way I see it. I'm very happy. I have a contract and I am very happy. I don't think that much about it," he said.
"I wouldn't lie, yes, it would be nice but I have a year-and-a-half contract and there's no difference when you consider what happened to Ranieri. The biggest one and the best one.
"Who has the safest job? We would all say Ranieri. Everyone would have said that. Ranieri. And then what happened with that? So I'm not that bothered about that to be fair."
