LAS VEGAS – Ryan Garcia emphatically answered his enormous army of critics Saturday night.

The popular, polarizing prospect impressively knocked out Romero Duno in the first round of their scheduled 10-round lightweight bout. Duno was supposed to provide the toughest test of the 21-year-old Garcia’s career on the Canelo Alvarez-Sergey Kovalev undercard at MGM Grand Garden Arena.

Instead, Garcia knocked down Duno with a perfectly placed right hand to the temple. Duno fell to the seat of his trunks.

The Filipino fighter attempted to get up, but referee Tony Weeks wisely stopped their fight 1:38 into the first round.

“I feel good,” Garcia told DAZN’s Chris Mannix after his knockout win. “It’s kind of what I expected, like I said. But all respect to Duno. He came to fight. He came in shape. He caught me with that overhand right. You seen right on the chin, and I took it. And then, from there, I knew I could just keep taking ‘em and keep coming at him. So, when I took his best shot, I felt good. I was like, ‘All right, I got him.’ ”

Garcia (19-0, 16 KOs), of Victorville, California, won the vacant WBC silver lightweight title. He also took the NABO 135-pound championship from Duno (21-2, 16 KOs).

Duno’s only previous loss was an eight-round, unanimous-decision defeat to Mikhail Alexeev (12-1, 4 KOs) in May 2016.

Garcia could’ve fought Duno seven weeks before Saturday night, but he understandably turned down Duno as an extremely late replacement for Avery Sparrow in mid-September. Philadelphia’s Sparrow (10-1, 3 KOs, 1 NC) was arrested the day before he was supposed to box Garcia on September 14 at Dignity Health Sports Park in Carson, California.

Duno was already scheduled to box Ivan Delgado on that card, but Duno and Garcia’s handlers at Golden Boy Promotions wanted to put together a Garcia-Duno bout once the Garcia-Sparrow fight fell apart.

Once Golden Boy made it known Garcia didn’t want to fight Duno on short notice, it caused a brief rift between Garcia and his promoters. Garcia signed a contract extension with Golden Boy, though, and quickly agreed to fight Duno on Saturday night.

Keith Idec is a senior writer/columnist for BoxingScene.com. He can be reached on Twitter @Idecboxing.