Brad Shields has left England's training camp in Italy after sustaining a foot injury, with Alex Dombrandt called up as his replacement.
The 28-year-old back row has damaged ligaments in his foot and has been sent home for further tests.
Harlequins' Dombrandt, who has enjoyed a standout first season as a professional and was named in a preliminary training squad last month, will fly out to join the rest of the group on Thursday.
Eddie Jones' men are spending 12 days in Treviso as part of their preparations for the World Cup, which gets underway in Japan in September.
England, who face Wales, Ireland and Italy in internationals before the start of the tournament, begin their campaign against Tonga in Sapporo on September 22.