Matthews was the headline attraction on the Roots 31: Rock Stone card on Saturday at the Melbourne Pavillion, but was on the end of a second-round knockout by Queensland opponent Sunny Mawer.
Mawer committed to a right hand, then, with his back to Matthews, followed into a left backfist that connected flush, the official immediately stopping the fight.
“I wasn't expecting it, it came out of nowhere,” Matthews said.
“I thought I was in a safe position and then I guess I wasn't.”
The defining moment came after a back-and-forth first round, Matthews feeling he was well in the contest before the finish.
“I definitely thought it was shaping up,” he said.
“It was going to be a good fight, back and forth.
“I thought I hurt his leg a little bit and I thought I could roll forward with that but obviously I got caught.”
After a quieter 2025, Matthews is looking for a more active 2026, and is headed into recovery as he looks for his next opportunity.
Matthews was originally scheduled for the semi-main on this card, but was moved into top spot after brother Daniel Matthews’ main event bout fell through.