LAS VEGAS - Shane Mosley landed the crushing left hook, then turned and climbed the ropes in one elegant motion. Behind him, Fernando Vargas crumpled gracelessly to the canvas. This rematch wasn't much of a match at all, and Sugar Shane was back on top. Mosley stopped Vargas in the sixth round of their 154-pound rematch Saturday night, flattening Vargas with a walloping left hand for his second victory in the rivalry in five months. A grotesque swelling that closed Vargas' left eye caused the fighters' first match to be stopped in the 10th round in February. But even with two good eyes, Vargas never saw that hook - and the smaller Mosley hit him with a near-perfect punch. “It does boost my confidence knowing that I can knock out bigger guys,” Mosley said. “My power is increasing from fight to fight. I've noticed more of a snap to my punches. I've noticed that I can knock people out. I've hurt people very well.” The charismatic four-time world champion is back in form after four losses from 2002-04, and he might get a matchup with Floyd Mayweather Jr. or Antonio Margarito if he drops to 147 pounds. But nothing will happen until 2007: After beating Vargas twice in five months, Mosley will take the rest of the year off. Mosley was more aggressive and sharp from the opening bell, patiently landing the right hand that hurt Vargas repeatedly in their first fight. Vargas seemed frustrated and disorganized, never winning a clear-cut round. Mosley opened a cut above Vargas' right eye in the fifth round, but neither fighter had done much in the sixth until Vargas failed to block that crushing left from Mosley, buckling Vargas' knees. “I thought I was doing well up until the left hook,” said Vargas, who never even saw the punch until he watched the replay. “I thought it was slowly going my way. ... He caught me with a great shot, and I'm not going to take anything away.” Vargas eventually got up, but couldn't defend himself from Mosley's final blows. Referee Kenny Bayless stopped the fight with 22 seconds left in the round. “When I was in the ring, I remembered watching Oscar (De La Hoya) fight Vargas, and he threw that perfect left hook,” Mosley said, referring to the Golden Boy's 11th-round TKO of Vargas four years ago. “I was bouncing around, and I saw the opportunity, and I threw the perfect left hook again.” Vargas appeared weaker from the start, perhaps suffering from his weight fluctuations before the fight. He made weight on Friday, then apparently gained close to 14 pounds of hydration before the fight - which might have slowed him down. But Mosley had a masterful plan in his first fight since reuniting with his father, Jack, who had trained him since his youth. They split after Sugar Shane's second straight loss to Winky Wright in November 2004, but reunited for this fight with no hard feelings - and an excellent result. “We were in the gym working real hard, and he was very inspirational, not only to me, but to everyone in the camp,” Mosley said. Vargas was infuriated when the first fight was stopped, claiming he could have kept fighting despite the baseball-sized swelling that closed his eye. The rematch was quickly set, thanks to the first fight's entertaining matchup and impressive pay-per-view sales. Though both fighters are from Southern California, the MGM Grand Garden crowd of 9,722 was solidly behind Vargas, whose Mexican-American fan base loves his mercurial style. After Vargas was cheered, Mosley received a chorus of boos when he entered the ring in a red sequined jacket. Before the fight, both boxers said their rivalry was unlikely to be a trilogy. Vargas plans to move up to 160 pounds, while Mosley almost certainly will go down to 147. “Never again will you see me at 154,” said Vargas, who was jovial in his post-match news conference. “You people don't understand what it takes for me to get down to 154. ... It's insane.” Both fighters drank water in their corners - and that was a big deal in some boxing circles. Mosley's promoters got a temporary injunction Friday night preventing Vargas from drinking Gatorade during the fight, something that became legal earlier in the week with new rules adopted by the Nevada Athletic Commission. HBO will replay the fight next Saturday.