Mullins a K.O. Victim
When the bell sounded, K.O. Mullins responded with alacrity.
He sprang from his stool and charged across the ring, showing
disdain for the strength of the champion. Although his belligerent
attitude impressed the referee, it failed to intimidate the champ.
The intrepid battler laid the hapless Mullins low with an adroit
feint and an uppercut.

To throw down the gauntlet--The principal of our rival school threw
down the gauntlet, and we had no choice but to accept the challenge.
(to challenge someone)