German boxer Viktor Jurk scored one of the fastest knockouts in history, flooring Edwin Castillo with one punch just seconds into their bout on Friday night.

The unbeaten fighter came into the fight with a significant amount of hype in his homeland, and just moments after the bell rang in Mannheim, he showed what he was capable of.

Jurk strolled to the centre of the ring and unloaded a mammoth left hook to the jaw of his Colombian opponent, which turned his lights off in an instant.

The stunning victory shook the boxing world, with many taken aback by the power Jurk possesses.

However, there have also been question marks over whether Castillo was actually intending to touch gloves at the start of the first round, which is why his hands were low.

He seemingly extended his left glove toward the 26-year-old German, but the southpaw took advantage.

Castillo hit the decks, rolled onto his back, and spread his arms wide before lying there motionless as the referee gave him the count.

The commentator for DAZN seemed confused as to why the referee even needed to count, given how out of it Castillo appeared.

'Unbelievable. Not sure why the referee is counting,' he said. 'I joked it could end in 30 seconds, and it didn't even last that.'

Soon enough, the referee waved it off, and Jurk took his undefeated record 14-0, with 12 of those victories via knockout.

The bout was on the undercard of the IBF welterweight title eliminator between Irishman Paddy Donovan and Ukraine's Karen Chukhadzhian at the SAP Arena.

Donovan took a huge step toward another chance to win the belt by securing a majority decision victory, with the judges scoring it 115-111, 114-112, 113-113.