Social media reacts to controversial one-punch knockout in boxing match

A boxer was knocked out within the first five seconds of a bout on Friday, but many fans have red flags up.

Edwin Castillo, 23, lost his fight to Viktor Jurk, 26, in a heavyweight fight on the undercard of Karen Chukhadzhian vs. Paddy Donovan in Germany.

Jurk landed a devastating left hook just as the two met in the middle of the ring, and Castillo went right down to the canvas.

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Jurk was rather nonchalant following the punch as Castillo lay on the floor...