England striker Daniel Sturridge has been sent for a scan after he was injured in training on Friday.
The Football Association has not revealed the nature of the injury and says Sturridge will be assessed by England's medical staff after his scan.
Liverpool forward Sturridge, 25, played 89 minutes of the 1-0 friendly win over Norway at Wembley on Wednesday.
Roy Hodgson's men face Switzerland in their opening Euro 2016 qualifier in Basel on Monday.
Defender Gary Cahill missed training on Friday with an ankle problem but is expected to be fit to take part in Saturday's session.
|Daniel Sturridge factfile|
|Signed for Liverpool in January 2013|
|Former clubs are Coventry City (youth), Manchester City, Chelsea and Bolton Wanderers (loan)|
|Made England debut in November 2011 against Sweden|
|Represented Great Britain at the London 2012 Olympics, scoring twice|
|Scored 21 goals for Liverpool in the 2013-14 Premier League season|
Speaking at a news conference at St George's Park, Cahill said of Sturridge: "We have our fingers crossed because he's a key player for club and country. He has been fantastic of late and he's a big player."
Sturridge, who has scored five goals in 16 international appearances, left Liverpool's pre-season tour of the United States early after injuring a hamstring.
He played in the Reds' first three Premier League matches, scoring the winner in the 2-1 opening-day victory over Southampton.
If Sturridge misses the match against Switzerland, Hodgson will have captain Wayne Rooney, Liverpool's Rickie Lambert and new Arsenal signing Danny Welbeck as his attacking options.
Chelsea central defender Cahill believes the game will be one of England's toughest tests in a qualifying group also featuring Slovenia, Estonia, Lithuania and San Marino.
The 28-year-old asked for supporters to show patience as England seek to rebuild following their early World Cup exit and the international retirements of experienced midfielders Steven Gerrard and Frank Lampard.
"Switzerland will be confident, but it is a great opportunity to bounce back from a disappointing summer," he said.
"Turning around our fortunes is not going to happen overnight - everyone knows and expects that.
"This group of young players is the one we have got moving forward for the next couple of years. Everyone needs to be patient."