The volatile striker has also clashed with one of the Chelsea fitness coaches over an injury that he feels he has been carrying, and he did not travel to Leicester with his team-mates on Friday. Costa has not trained fully this week and the manager, Antonio Conte, has become involved in the argument.
It is the situation involving the Chinese club that has led to the greater consternation at Stamford Bridge.
Costa, in common with an increasing number of leading Premier League players, has been the subject of an eye-watering £30m per year offer from China and there is the fear at Chelsea that his advisors could be using it to lever him away. Costa’s agent, Jorge Mendes, is reportedly in China.
Costa has recovered his best form this season and his goals have been instrumental in Chelsea’s surge to the top of the table.
Still, the Blues’ hierarchy have taken a dim view of the situation regarding China and, amid fears that the 28-year-old’s head might have been turned, they have pledged to hold him to his contract, which expires in 2019.
Conte said at his press conference on Friday afternoon that he had at least one decision to take in terms of his selection for the Leicester game.
“I have to check a couple of situations and then decide,” he said. “I don’t want to say exactly what and give an advantage to our opponent.”
He was also asked, in relation to Dimitri Payet going on strike at West Ham United, whether he had experienced any issues about players refusing to play for him.
“It’s very difficult to talk and above all for me, it’s very difficult for me to talk about another player,” Conte replied.
“For my club, for my players, we solve our problem if there are problems. This is important.”
Conte has just won the Premier League’s manager of the month award for a third successive time – a record – on the back of his team’s 13-match winning streak but after their 2-0 defeat at Tottenham Hotspur on 4 January, he has been consumed with bouncing back. He could have done without this latest headache involving Costa.
EDITED FROM: theguardian.co.uk