Roman Gonzalez of Nicaragua enhanced his reputation as one of the world's best pound-for-pound fighters on Saturday after easily defeating Puerto Rico's McWilliams Arroyo to retain his World Boxing Council flyweight crown.

The 28-year-old champion improved his record to 45-0 (38 knockouts) to claim a unanimous decision over the game but outclassed Arroyo in a bruising 12-round contest at Los Angeles's iconic Forum sports arena in Inglewood.

Two judges scored it 119-109 in Gonzalez's favor with the third card marked at 120-108. The scores did not flatter the champion.

It was Gonzalez's fourth defense of the title he won after beating Japan's Akira Yaegashi in Tokyo two years ago.

After a cagey first round, Gonzalez began to gain the upper hand from the second onwards, hounding Arroyo around the ring and peppering his opponent with flurries of precise shots to the body and head.

Gonzalez rocked Arroyo with a jolting left midway through the third round that left the Puerto Rican wobbling before closing with another combination.

Arroyo's task was made harder in the fourth round when the sole of one of his boots flew off, leaving him clearly distracted as Gonzalez dominated again.

Arroyo however appeared determined not to become Gonzalez's 39th knockout victim, and did well to continue to evade trouble as the champion stalked him relentlessly around the ring.

With Gonzalez comfortably ahead going into the later rounds, Arroyo needed something special to produce an upset.

But after going toe-to-toe with Gonzalez towards the end of the 11th, Arroyo was unable to conjure the knockout required to depose the champion, who held on with relative ease for the win.