Gareth Southgate could be without Phil Jones and Fabian Delph ahead of England's upcoming fixtures during the international break.
The Manchester-based pair, who both look to be in pole position for a Premier League title fight with their respective clubs this season, didn't train with the England squad on Monday and both players are going to be assessed by medical staff prior to the Three Lions hosting Slovenia on Thursday.
Preston-born defender Jones has been a vital player for Manchester United this season, featuring in all seven Premier League outings for the Red Devils. Jones joined United from Blackburn Rovers for £17m in 2011 and has gone on to make 174 appearances over the last six years.
England could also be without versatile midfielder Delph, who has shown his quality in recent matches acting as a temporary stopgap for the injured Benjamin Mendy at left-back for Pep Guardiola's side.
Delph has largely been a part-time player for City since completing a £10m move to the Etihad from Aston Villa in 2015, making just 45 appearances across all competitions. After scoring a screamer in Manchester City's 5-0 hammering of Crystal Palace last week, Delph has been given a chance to impress at full-back in consecutive matches against Shakhtar Donetsk and Chelsea.
Leicester City striker Jamie Vardy is a confirmed absentee from the Three Lions squad, the 30-year-old overcoming a minor hip injury despite featuring for the Foxes against Bournemouth on Saturday.
England will also be missing midfield talisman Dele Alli for their hosting of Slovenia on Thursday, the Tottenham star picking up a one-match suspension for a gesture he made whilst on international duty against Slovakia last month.