Luis Collazo, left, takes a punch from Edwin Cassiani in their welterweight bout at the Fremont Street Experience on April 13, 2002. Collazo suffered his first professional loss in the bout when he wilted in the outdoor ring during a 91-degree day. Review-Journal File Photo Welterweight Luis Collazo will take on Shane Mosley in the 12-round main event at the Mandalay Bay Events Center on Saturday. The Associated Press

Luis Collazo's only previous boxing experience in Nevada is one he won't soon forget. He faced an opponent that day tougher than any other he's seen.

The heat.

Collazo fought Edwin Cassiani in an outdoor ring on Fremont Street on April 13, 2002. The high temperature -- which occurred around the time Collazo climbed into the ring -- was 91, though with the heat radiating from the concrete, it felt much hotter.

"I thought it was about 140," Collazo said Wednesday, chuckling.

He can laugh about his first professional loss now. He's overcome the disappointment of that day, when he was stopped in the third round after nearly wilting in the oppressive conditions.

Collazo will face Shane Mosley in a 12-round welterweight bout Saturday in the main event of a Golden Boy Promotions card at Mandalay Bay, which he sees as an opportunity to establish himself as one of the sport's elite.

Collazo is 27-2, with his only other loss coming to Ricky Hatton last May 13, and at 25 has reached his prime. He believes he'll prove that against Mosley, a future Hall of Famer who has had a lot more success lately at higher weights.

Mosley is 2-2 in his last four welterweight bouts, having defeated David Estrada and Jose Luis Cruz in lackluster bouts in 2005 at 147 pounds. He's coming off back-to-back victories over Fernando Vargas in super welterweight bouts, but Collazo isn't intimidated.

Mosley is 35 and has been the quicker fighter in nearly all of his fights. But Collazo is convinced he'll hold that advantage Saturday.

"You have to have a lot of respect for Shane and what he's accomplished, but I believe this is my time," said Collazo, who won the WBA welterweight title from Jose Antonio Rivera on April 2, 2005, and made one successful defense before losing to Hatton. "My speed is going to be a factor, but I'm not one-dimensional. I can do whatever I have to do to win."

Collazo said the experience of the Hatton fight has been beneficial during his preparations for Mosley.

There are a lot of similarities in facing a high-profile opponent and Collazo has made adjustments in his mental approach.

"I was the champion, but the show was all about Hatton," Collazo said. "It's a lot of the same this time. Shane Mosley has a big name and it's about him. But I can go in with no pressure and do what I do. I had a point to prove to the media and the fans the last time, but I don't have anything to prove now.

"People who watch this sport know what I can do. I am a known quantity. I just have to go out and execute."

And, he said with a laugh, it's sure to turn out better than his last trip to Nevada. He was an up-and-coming unbeaten welterweight in those days who chose to wear a velour outfit on a scorching hot day.

His sweat made the trunks feel as if they weighed several pounds and it wasn't long before they stuck to his body.

"You try to learn from all of your experiences, and what I learned from that is to pick my outfit to suit the circumstances," he said. "No velour when you're fighting in the heat outdoors."