Arsenal forward Danny Welbeck remains in hospital after suffering a serious ankle injury on Thursday night.
Arsenal say Welbeck continues to be assessed and that a further update will be issued over the next 72 hours.
The England forward landed awkwardly in the first half of the 0-0 draw with Sporting Lisbon and received oxygen on the pitch, before being stretchered off with his leg in a brace.
And head coach Unai Emery said after the match: "The worst news tonight are these injuries. We think it's a serious injury.
"He broke something in his ankle and it's a different injury than another.
"Now he's at the hospital and the news is at the moment we are going to wait, but we think this is a serious injury."
The 27-year-old Welbeck, whose career has been blighted by knee injuries, was a regular for Arsenal last season and earned a place in the England World Cup squad.
He was named in the England squad on Thursday for the upcoming internationals against the USA and Croatia.
Sky sources understand manager Gareth Southgate is not likely to call up a replacement, given the number of players in the selected.