Danny Cipriani has been left out of England's latest training camp in Treviso, Italy.
The Gloucester fly-half was named in the official World Cup training squad earlier this month.
But the Premiership player of the year is not among a 38-man group travelling to Italy on Monday for a 12-day camp.
"We have left some good players doing work at their clubs and they must be ready if called up," said head coach Eddie Jones.
Cipriani was part of a small group of players who spent last week's Bristol training camp doing specialised strength and conditioning work off-site.
But while the Bath pair of Sam Underhill and Anthony Watson are both travelling to Italy this week, Cipriani, who is not injured, has been left at home.
While the RFU says Cipriani will continue to train with an England programme and is certainly not out of contention, his absence suggests his chances are slim of making the final 31-man World Cup squad, which is named on 12 August.
Exeter prop Ben Moon has also been omitted, while Harlequins centre Joe Marchant has been called up.
Experienced full-back Mike Brown is also included after initially missing out on selection.
The trio of injury concerns - prop Mako Vunipola, lock George Kruis, and wing Jack Nowell - are all involved.
"Treviso is a hard-yards camp with conditions similar to Tokyo," Jones explained.
"Team training will be about being adaptable and off the field enjoying each other's company."
Jones will finalise his World Cup party the day after England's opening World Cup warm-up match, which is on Sunday, 11 August against Wales at Twickenham.
England then face Wales in Cardiff, and Ireland at Twickenham, before their final pre-World Cup game, against Italy in Newcastle on Friday, 6 September.
England training squad
Forwards: Dan Cole (Leicester Tigers), Luke Cowan-Dickie (Exeter Chiefs), Tom Curry (Sale Sharks), Charlie Ewels (Bath Rugby), Ellis Genge (Leicester Tigers), Jamie George (Saracens), Maro Itoje (Saracens), George Kruis (Saracens), Joe Launchbury (Wasps), Courtney Lawes (Northampton Saints), Lewis Ludlam (Northampton Saints), Joe Marler (Harlequins), Brad Shields (Wasps), Kyle Sinckler (Harlequins), Jack Singleton (Saracens), Sam Underhill (Bath Rugby), Billy Vunipola (Saracens), Mako Vunipola (Saracens), Harry Williams (Exeter Chiefs), Mark Wilson (Newcastle Falcons / Sale Sharks)
Backs: Mike Brown (Harlequins), Joe Cokanasiga (Bath Rugby), Elliot Daly (Saracens), Owen Farrell (Saracens), George Ford (Leicester Tigers), Piers Francis (Northampton Saints), Willi Heinz (Gloucester Rugby), Jonathan Joseph (Bath Rugby), Joe Marchant (Harlequins), Jonny May (Leicester Tigers), Ruaridh McConnochie (Bath Rugby), Jack Nowell (Exeter Chiefs), Henry Slade (Exeter Chiefs), Ben Spencer (Saracens), Ben Te'o (unattached), Manu Tuilagi (Leicester Tigers), Anthony Watson (Bath Rugby), Ben Youngs (Leicester Tigers)