The Everton midfielder pulled out of the squad for the forthcoming Euro 2020 qualifiers with Czech Republic and Bulgaria today.
Delph picked up a muscle in Everton’s defeat 1-0 at Burnley on Saturday, despite completing 90 minutes in the game.
The 29-year-old has been assessed and advised to withdraw from Gareth Southgate’s squad so he can undergo treatment with his club medics.
England have no plans as yet to call up a replacement for Delph in what is now a 24-man squad for the two away games.
England joined up at St George’s Park today, and are training this afternoon.
Several players though are expected to miss the session, including all of those who played for their club sides yesterday.
Chelsea forward Tammy Abraham meanwhile is being assessed by the England medical team.
Abraham, called up by England for the first time since 2017 last week, suffered what appeared to be a hamstring strain during Chelsea’s 4-1 win at Southampton, in which he scored his ninth goal of an impressive campaign so far.
Goalkeepers: Tom Heaton (Aston Villa), Jordan Pickford (Everton), Nick Pope (Burnley)
Defenders: Trent Alexander-Arnold (Liverpool), Ben Chilwell (Leicester), Joe Gomez (Liverpool), Michael Keane (Everton), Harry Maguire (Manchester United), Tyrone Mings (Aston Villa), Danny Rose (Tottenham), Fikayo Tomori (Chelsea), Kieran Trippier (Atletico Madrid)
Midfielders: Ross Barkley (Chelsea), Jordan Henderson (Liverpool), James Maddison (Leicester), Mason Mount (Chelsea), Declan Rice (West Ham), Harry Winks (Tottenham)
Forwards: Tammy Abraham (Chelsea), Harry Kane (Tottenham), Marcus Rashford (Manchester United), Jadon Sancho (Borussia Dortmund), Raheem Sterling (Manchester City), Callum Wilson (Bournemouth)