By Chelsea correspondent Tony Hughes| Premier League expert with experience of breaking big stories, including exclusives like this

Chelsea are sweating on the fitness of Diego Costa and Eden Hazard ahead of their showdown against Arsenal on Sunday, Football Insider sources understand.

Costa was rushed to hospital on Saturday night for scans on a shin injury sustained in Chelsea’s 3-3 Premier League thriller with Everton.

A Chelsea source has told Football Insider that the Spaniard will undergo further tests at the club’s Cobham headquarters on Monday but the early signs are that there is only bruising to his tibia, and crucially no break or fracture.

Costa now faces a race against time to be fit for the champions’ Premier League trip to Emirates Stadium on Sunday.

Manager Guus Hiddink has said Hazard must prove his fitness in training this week after missing Chelsea’s last three matches with a hip injury.

“We have to be a little bit careful that we don’t fall again with a setback,” Hiddink explained.” That’s why I say he must have some tough training sessions. From Tuesday to Thursday he must have intense training sessions. Then we’ll decide if he can join us in the Arsenal game next weekend.”

Against Everton, Costa scored a goal and supplied an assist as Chelsea fought back from 2-0 down before limping off at the 80-minute mark with the score at 2-2.

Initially, it appeared that Costa had gone down holding his calf but manager Hiddink revealed afterwards that he had a shin problem.

Fitness race: Hazard has missed Chelsea's last three games with hip injury

Fitness race: Hazard has missed Chelsea’s last three games with hip injury

“He’s in the hospital now for a scan but we don’t know the result,” explained Hiddink at his post-match media conference. “It’s on his shin. He was in a lot of pain but as soon as we know what is in the report we will put it out there.”

Costa has scored five goals in five games under Hiddink and the Blues boss cannot afford to lose the striker to a lengthy spell on the sidelines.

Hiddink confirmed that despite his lack of options, Chelsea were not in negotiations with any club over signing a new striker.