The 26-year-old was replaced by Nathan Hughes near the end of the first half in England’s defeat to the Springboks.
Woke up this morning as a genuine book winner! Last night my book Wrecking Ball won Rugby Book of the Year at the Sport Book Awards 2018 @sportbookawards #SBA18 Thanks @Wasserman & @GershonPortnoi ?? #WreckingBall pic.twitter.com/RSwVd53GdS
The No.8 will be assessed further next week to determine the extent of his injuries.
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.