VIDEO: How Vunipola broke his arm
VIDEO: How Vunipola broke his armSHARE
The injury occurred as he swung a flailing arm at Rob McCusker, which connected with the Ospreys No.8's head, sending both players to the turf in a lump.
Despite clutching his arm, Vunipola played on and finished the half, taking part in defence as well as making a drive from a line-out. He even helped big Maro Itoje up from the floor, which couldn't have helped any.
Vunipola didn't return after half-time, and after the match said that he couldn't feel his wrist.