Billy Vunipola will return home early from England's tour of South Africa after re-fracturing his right arm during the second Test in Bloemfontein.
The Saracens back-rower suffered the injury during the first half of his side's 23-12 loss, a result that means the tourists are playing only for pride in the series finale next Saturday.
Vunipola - who was replaced by Nathan Hughes before the interval - broke the same arm while playing for his club in the European Champions Cup in January.
The 25-year-old will undergo further assessment in London in the coming days, according to a statement released by the Rugby Football Union (RFU) on Sunday.
England will also be without the other Vunipola for the third Test next Saturday, though Billy's older brother Mako has departed for family reasons, as agreed with the RFU prior to the squad travelling to South Africa.
Head coach Eddie Jones has called up Exeter prop Alec Hepburn to bolster his front-row options for the game in Cape Town on June 23, as England look to end a five-Test losing streak.