RENO, Nev. -- Marco Antonio Barrera knocked down Enrique Sanchez twice Saturday night before referee Vic Drakulich stopped the non-title featherweight fight at the end of six rounds after conferring with Sanchez's corner.

"It was retirement by the corner. They felt he had enough and I agreed with them," Drakulich said.

Barrera, 54-3 with 39 knockouts, used his jab with almost as much effect as his right against his fellow Mexican in the scheduled 12-rounder. Sanchez, 28-2-2, fought gamely but with little effect against his more powerful opponent.

"I could have been a little more stable with in-punching, but I felt very comfortable against Sanchez," Barrera said.

Leading up to the main event at Lawlor Events Center, Vassiliy Jirov used awesome body shots to slow Julian Letterlough, then went to the head to stop him in the eighth round and retain his IBF cruiserweight title.

Jirov, 30-0 with 26 knockouts, went quickly to the belly of his shorter, stockier opponent, but mixed in head shots along with pesky right jabs that kept Letterlough off balance. Letterlough, 17-2-1, never mounted a serious offense.

Jirov, the light heavyweight gold medalist at the 1996 Olympics from Kazakhstan, maintained steady pressure on Letterlough. The pace slowed in the sixth and seventh rounds, drawing boos from the crowd.

Jirov responded with his eighth-round attack, stunning Letterlough with a left to the temple a minute into the round, then finishing him off with a flurry in Letterlough's corner until referee Jay Nady stopped it at 1:24.

"I showed the people I can fight. I can box," Jirov said. "Letterlough slowed down toward the end, but he is a very dangerous puncher and I had to be wary."

Jirov next has his sights set on James Toney, a former IBF middleweight champion and super middleweight champion, and eventually hopes to unite the title with fights against Virgil Hill, the WBA champion, and WBC champion Juan Gomez.

On the undercard, Fernando Montiel of Mexico weathered a dogged attack -- and four low blows -- to retain his WBO flyweight title with a unanimous decision over Jose Lopez of Puerto Rico. Montiel is 23-0-1, while Lopez slipped to 24-6-1.