Danny Welbeck could face a lengthy spell on the sidelines after Arsenal described his ankle injury as “significant”.
Welbeck was carried off on a stretcher on the half-hour mark of Thursday’s Europa League stalemate with Sporting Lisbon.
The England forward continues to be assessed, with the Gunners set to provide a further update on his condition in the next 72 hours.
He is expected to miss his country’s fixtures against the United States and Croatia during the upcoming international break, having been named in Gareth Southgate’s squad earlier on Thursday.
“Danny remains in hospital and will continue to be assessed,” the club posted on arsenal.com on Friday afternoon.
“A further update will be issued over the next 72 hours.”
Welbeck has endured a wretched injury record during his career with knee issues costing him months on the sidelines.
His latest setback comes after he landed badly on his right ankle having jumped for a header in the 25th minute of the Group E encounter at the Emirates Stadium.
The 27-year-old received oxygen on the pitch and had his leg in a protective brace as he was taken off.
Gunners head coach Unai Emery admitted after the goalless draw – which assured Arsenal’s qualification for the knockout stages – that Welbeck’s injury weighed heavy on his players.
Team-mate Rob Holding has backed Welbeck to make another comeback and insists the Arsenal players will rally around their colleague.
“I didn’t see it because obviously I’m at the other end of the pitch so I didn’t see exactly what he’d done,” said Holding.
“But Danny is a tough lad so if he’s on the floor, I know its something serious and he’s gone off to hospital now and we’ll see what happens.
“He’s been so unlucky with injuries over the past few years but he’s a good character and got a good set of lads around him so we’ll lift him up and get him back as soon as we can.
“He can come back strong.”
Chelsea midfielder Ross Barkley anticipates some hostility from Everton’s visiting supporters in Sunday’s Premier League clash at Stamford Bridge.
The 24-year-old moved to Chelsea in January after 13 years at Goodison Park and faces the Toffees for the first time in opposition colours.
“I don’t think it (the reception) will be the best,” Barkley said in the London Evening Standard.
“I’m not nervous, I’m excited to play against my former club and team-mates – I understand how some of them play, so that could be an advantage for me.
“On the day I might get a few nerves as it will feel a bit strange. I’m looking forward to catching up with some of the staff there who I used to get on really well with.”
Barkley did not play for Everton in the last seven months of his spell due to a hamstring problem and moved in a cut-price £15million deal, with his contract winding down.
He has previously insisted it was time to move on and make progress, and he has impressed Chelsea head coach Maurizio Sarri while scoring three goals in his last five Blues appearances.
“I was approaching 25 and I felt looking back I could have improved a lot more (at Everton),” Barkley added.
“At Chelsea I knew I’d improve a lot quicker around better players, world-class players.”
Barkley has played in the last three games, so may drop to the bench against the Toffees.
Alvaro Morata could return up front, despite Olivier Giroud ending a six-month barren streak in goal with the decisive strike in Thursday night’s 1-0 Europa League Group L win at BATE Borisov in Belarus.
Giroud quipped he contemplated seeking religious help, prior to ending a run of 794 minutes without a Chelsea goal.
Giroud told Chelsea TV: “It’s true I’ve been looking forward to it. I kept working hard in training, kept the faith. I always score goals.
“At the end of the day it has to come back. I didn’t know when, but I’m glad.
“I’m happy for the team and for myself I hope I will have the opportunity to score more.
“I was thinking shall I see a priest or something like that? No, I’m joking.”
Sarri was far from satisfied with the performance at BATE, despite sealing qualification for the knockout stages with two matches to spare, and is likely to restore rested defenders David Luiz, Antonio Rudiger and Marcos Alonso.
Midfielder N’Golo Kante was a late call-up for the trip following illness to Cesc Fabregas, but the Frenchman did not feature and is likely to start against Everton as Chelsea bid to extend their unbeaten run to 18 games.
Fabregas and Ruben Loftus-Cheek, who has a minor back problem, are the only doubts.
Giroud added: “Everything is not perfect, but we work on it.”
Manchester United manager Jose Mourinho is ready to go toe-to-toe with “untouchable” Manchester City in this weekend’s eagerly-anticipated derby.
Pep Guardiola’s Premier League leaders lie in wait at the Etihad Stadium on Sunday as United look to emerge from a daunting double-header with another memorable away win.
Cristiano Ronaldo’s stunning volley was rendered meaningless on Wednesday as Mourinho oversaw a late 2-1 Champions League comeback win at Juventus – a side bracketed with City as among the continent’s best.
Wednesday’s 6-0 defeat of Shakhtar Donetsk underlined the quality of Sunday’s opposition, but life off the field is not as rosy as City face allegations that they have tried to cheat European football’s Financial Fair Play rules.
Asked if he felt United were operating on a fair playing field ahead of the derby, Mourinho said: “It’s difficult for me to answer because I focus on my job, I focus on the four lines.
“I focus on football. If you want to speak about their football potential, we can speak.
“And football potential starts with investment. After that, of course, there is a quality of the work and the quality of the organisation and I think that is untouchable. But what is behind, I cannot say.
“But, in this moment, I have only to think about football, and to think about football is just to think about Manchester City as a football team.”
The allegations about City’s finances have been made by German publication Der Spiegel, citing documents and private emails obtained from the whistle-blowing group football Leaks.
City have described the reports as the product of an organised attempt to damage the club’s reputation, based on “materials hacked or stolen”.
Mourinho sidestepped the allegations against Sunday’s opponents and instead praised a side that he hopes to go toe-to-toe with, just as he did at Juventus and in the recent 2-2 draw at Chelsea.
The United boss said: “We are going to try. I cannot say we are going to be successful in our motivations, in our desire, but we played two difficult matches away against two very good teams, Chelsea and Juventus, and we managed to get good results.
“And even if the good results were not in our pockets, the performances were there, the positive attitude was there, so we are going to try. But you are right, Manchester City is a very powerful team.”
Yet United know they can hurt Guardiola’s side, having come from behind to win 3-2 at the Etihad Stadium in April and delay their title party.
City are on course to retain the Premier League crown, but Mourinho is not getting worked up about cutting back a gap that already stands at nine points.
“If we drew it’s nine, if we lose it’s 12,” the United boss said. “I don’t think it’s the way to look at the match.
“You know, I think we have to just think about the match. The match is difficult enough by being an isolated event. If you want to put that match into the context of where we are, where we can be, then it becomes even more difficult.
“So, I just want to play the match as an isolated event: difficult match against a very difficult team. But I don’t think they think it’s an easy match for them.”
However, Mourinho knows they cannot afford the sloppy starts that have been all to frequent recently.
He said: “If we keep conceding goals before the opponent, it will arrive the day where we cannot come back.
So, we have to make sure we grow up not just in our approach, – because that I think is clear that the team is growing up – but also we have to grow up in our compactness and to start matches well. Which, I have to say against Juventus, it happened.”
Romelu Lukaku missed the trip to Turin after picking up a hamstring complaint on the eve of the 2-1 win at Bournemouth, but the striker could make a welcome return at City.
Mourinho added: “Lukaku is training with the team this morning. We have of course one more session tomorrow, but if the answer is positive, he’s ready. But in this moment, I can only say he trains with the team. I don’t know his answer.”