Teenage striker Mason Greenwood is the latest Manchester United player to be struck down by injury.
Manchester United forward Mason Greenwood has pulled out of the England Under-21 squad due to injury.
The 18-year-old has withdrawn from Aidy Boothroyd's group because of a back problem and will remain with United during the international break.
Wolves' Morgan Gibbs-White (back) and Arsenal's Reiss Nelson (knee) have also pulled out of the England U-21 squad, with Swansea City's Sam Surridge and Ben Wilmot called up in their stead.
Greenwood, who came on as a substitute in Sunday's 1-0 Premier League defeat to Newcastle United, will now begin a battle to be fit for the visit of Liverpool on October 20.
He is the latest United player to be struck down by injury during a desperately difficult run for manager Ole Gunnar Solskjaer.
Paul Pogba, Jesse Lingard, Luke Shaw, Aaron Wan-Bissaka, Victor Lindelof, Eric Bailly, Phil Jones and Anthony Martial all missed the loss at St James' Park, which extended United's winless run to three games in all competitions.
Excluding the penalty shoot-out win over League One Rochdale in the EFL Cup, Solskjaer has overseen just three wins this season and none since the 1-0 victory over Astana in the Europa League on September 19.