London - Chelsea striker Diego Costa trained alone for the second day in a row on Monday at the club's training base, British media reported, as he recovers from an apparent back injury.
The Spain forward's Chelsea future was called into question after he was left out of the Premier League leaders' win at champions Leicester on Saturday amid speculation he could be the subject of a colossal bid from a wealthy Chinese club.
Manager Antonio Conte, however, was adamant it was injury - rather than an apparent fall-out with Costa - which prevented the 28-year-old featuring.
Costa, who has scored 14 Premier League goals in 19 appearances this season, will have his fitness evaluated again ahead of Chelsea's match at home to Hull on Sunday.
"If there is a problem - and I repeat 'if' - with the players then in my career I prefer to sort the problem in the changing room, not outside and not in a press conference," said Conte on Saturday.
"But I repeat - if. I have told the truth."
China says it will cut foreign player numbers in top-flight teams in a bid to curb massive spending on overseas talent.
Shanghai SIPG last month broke the Asian transfer record when they paid Chelsea €60 million ($63 million) for the Brazilian midfielder Oscar.