Chelsea manager Antonio Conte says he is unsure when Diego Costa will return from injury after leaving him out for Saturday's 3-0 win at Leicester.

Costa had a dispute with a coach over his fitness and Conte said the 28-year-old Spain striker complained of a back problem on Tuesday.

There were also reports he is the subject of an offer to move to China. external-link

"I don't know how long it will take, I don't have his pain," said Conte. "We'll see about this next week."

Costa has been integral to the Premier League leaders this season, having scored 14 goals and provided five assists.

BBC Match of the Day pundit Ian Wright said: "For Costa to come out at this stage when they need him so much feels very strange. He's scored 14 goals this season - you need someone like that in this team. It seems like it's derailed what's going on."

When asked if a move to China would surprise him, Wright said: "Absolutely not. Costa doesn't seem like the sort of person who cares what people think. Whatever happens - if it's his back it's very hard to detect - something has turned him."

Italian Conte, 47, was repeatedly questioned about the rumours surrounding the player after watching his side move seven points clear at the top of the table.

Asked whether Costa has a future at Stamford Bridge, he said: "I can't be concerned about this because today my players produced a great performance and showed spirit. I can't be concerned with nothing."

The former Juventus and Italy boss was then asked once more whether the Brazil-born forward would feature again for the Blues and responded with: "Why not?"

He added: "There are lot of 'if' questions - I don't like to answer these types of questions."

On reports of interest from China, Conte told BBC Sport: "I don't know and the club doesn't know anything about the reports of Costa to China. The truth is what I told you before."

Left-back Marcos Alonso, who scored twice against Leicester, said: "You guys [journalists] made up the story. Diego wasn't feeling well because of his back. He's very happy and will have a great season at Chelsea."

Analysis: 'If you get £60m, then let him go'

Former England defender Danny Mills on BBC Radio 5 live

Why shouldn't Diego Costa go to China? There is no loyalty from clubs in football.

He's already defected from Brazil, his native country, to play for Spain and has no real affinity with England and the Premier League. I'm sure he likes London but he doesn't have any real affinity here.

Brazilians move around all the time; they will go wherever the money is.

BBC football expert Mark Lawrenson

Well done Conte. If you get £60m, then let him go.

He's at his peak, the team is built around him totally. He is a top, top player, but if he wants to go to China and be bored 18 hours a day, good luck to him. If he went - and I don't think he will - they don't win the league.

Former Arsenal defender Martin Keown on Football Focus

Conte is reasserting himself. Costa has football utopia at the moment - top of the league, top of the scoring charts, what is wrong in his life? He will come back quietly with an apology.

I don't think it will derail Chelsea. He is a quality player who they can't do without, People tell me he goes off on one like this, but he will see sense.

It is a very difficult dressing room at Chelsea and the manager has done very well this season.