A few years ago I was watching an online stream of a club match between a Portuguese and a Spanish side. Near the end of the game with the Portuguese leading, the Spanish Scrum Half was preparing to take a box kick from a ruck 5-10m from the tryline, whilst the Portuguese 9 and a Prop were attempting to charge it down. The ball went, at full force, straight into the Prop's head concussing him. The two 9s scrambled for the loose ball, colliding and missing the ball as it rolled over the tryline. The concussed Prop meanwhile was staggering around, tripped over the two 9s and fell forward with an arm stretched out and grounded the ball for a try.