Chelsea returned to winning ways in their first appearance after the World Cup break, but delight at their 2-0 home victory over Bournemouth on Tuesday was tempered by new injury concern for Reece James.
The England right-back lasted only 53 minutes on his return from the knee injury that ruled him out of the World Cup in Qatar, leaving Chelsea fearing the worst as they await a more detailed examination and prognosis.
"He’s not good but we’ll have to wait and see. It’s too early for me to speculate but whenever he comes off like that, it is not positive," manager Graham Potter said.
Eight minutes into the second half, James signalled to the bench that he needed to come off before going down in some discomfort.
He looked distraught as he laid on the pitch at Stamford Bridge receiving treatment but did walk off on his own.
The 23-year-old had surgery after suffering a knee injury against AC Milan in the Champions League on October 11 and it was the knee that looked to be the cause of his anguish again.
"We’ll have to keep our fingers crossed and find out in the next day or two," added Potter.
Chelsea, who had not won in their last five league matches and started Tuesday’s game ninth in the standings, were rejuvenated with James in the right-back position as they scored twice in the opening 23 minutes to secure the three points.
James took no time at all to remind of his ability, especially as Chelsea swept forward with quick pace in a convincing performance.
On the eve of the match, Potter had said James was in a "good place" after the "challenging period" of missing out on the World Cup.
"It was a World Cup and they come around every four years. So when you're young, the perspective is not so easy to get," said Potter.
"I have to say he is in a good mood, he is in a good place. He has trained with us, is training well and is a good team mate. He has dealt with it well."
Rashford on song
England striker Marcus Rashford continued his fine goal-scoring form as Manchester United cruised to a 3-0 victory over Nottingham Forest.
Rashford, who scored three times for England at the World Cup in Qatar, set United on their way to victory with a well-placed finish from a corner in the 19th minute, before Anthony Martial doubled the hosts' lead three minutes later.
Forest thought they had got back into the match midway through the first half, but Willy Boly's goal from a free kick was ruled out for offside.
The visitors never looked like mounting a comeback, with United putting the seal on a impressive display as substitute Fred netted a late third, completing a victory that moves the fifth-placed hosts one point off the top four. Forest stay 19th.