Violent altercations in a game like rugby are not uncommon, so for raised eyebrows you'd need a pretty awful altercation. This series of punches in the English Premiership 11 years ago is definitely one of those.
England star Manu Tuilagi, then of Leicester Tigers, blindsided Northampton's speedster Chris Ashton off the ball, igniting the flame in their exchange. Ashton, obviously aggravated, shoved the Tigers centre in the back.
Tuilagi was straight to his feet, and threw three punches at Ashton, all connecting cleanly with his head. The third punch is particularly hard to watch as you can see the Northampton winger's head jerk back unnaturally. Remarkably, Ashton stayed on his feet after a flurry of blows with blood pouring from his head. It is not for the faint-hearted.