Costa has struggled badly for form since Chelsea refused to let him take up a £30million-a-year offer from Tianjin Quanjian who have reignited their interest in him.
Guangzhou Evergrande are also interested in signing the Spaniard but Tianjin Quanjian coach Fabio Cannavaro has made him his No1 target.
Chelsea stars in training as full-strength Blues prepare for Man United clash Fri, April 14, 2017
Express Sport brings you the best pictures from Chelsea's latest training session as the Blues prepare to take on Manchester United at Old Trafford on Sunday (4pm)
Play slideshow Getty Images 1 of 19
Chelsea were hard at work in training ahead of their clash with Man United
Diego Costa will leave Chelsea this summer
Tianjin Quanjian’s billionaire owner Shu Yuhui is still willing to pay the £90m that he offered in January for Costa, 28, who is under contract until 2019.
But Chelsea will only give their blessing to him leaving Stamford Bridge when they complete the signing of Real Madrid’s Alvaro Morata.
Alvaro Morata is set to quit Real Madrid at the end of the season
Morata is behind the likes of Cristiano Ronaldo, Gareth Bale and Karim Benzema in the Bernabeu pecking order and has set his heart on a move to London.
Real are demanding around £50m for Morata who is a target for Antonio Conte, having impressed during a loan spell at Juventus.
Get Quotes on Home Insurance