LAS VEGAS -- Roy Jones Jr. really didn't want to do this, and not just because he had to stop eating for a while. Surely, he figured, there were better fights out there for a heavyweight champion who had just made history.

Evander Holyfield was his first choice, but that couldn't be worked out. Ditto with Mike Tyson and Lennox Lewis.

So instead of fighting a second-tier heavyweight, Jones looked down, all the way down to the light heavyweight division he used to rule. There he found Antonio Tarver wearing his former belts, and talking just enough trash to provide some motivation.

Now he had another problem -- dropping all the weight he put on a few months ago to fight John Ruiz, to become only the second light heavyweight champion to win the heavyweight title.

"You're hungry, thirsty half the time. You start taking out your frustrations on everybody you come across," Jones said. "I wouldn't go down to this weight for nobody else but him. I wanted him to have the best opponent he could have so I came down for him to his weight."

That mission accomplished, Jones meets Tarver for the WBC 175-pound title Saturday night in what will likely be his last fight ever as a light heavyweight.

He's not too happy about having to lose the weight -- he was 193 pounds for Ruiz -- but Jones is more than eager to put on a show against a fighter he believes hasn't shown him the proper respect.

"He's going to pay for this," Jones said.

Tarver is the champion, but Jones is the attraction for the scheduled 12-round fight, which will be televised on pay-per-view beginning about 11:30 p.m. ET. The fight will follow a title defense by IBF 154-pound champion Winky Wright against Angel Hernandez.

Jones is an 8-1 favorite to add the light heavyweight title to the piece of the heavyweight crown the WBA generously allowed him to keep while he makes what he hopes will be his final foray into the lighter ranks before taking on Tyson next year.

"That will probably be my last fight," Jones said, referring to Tyson. "It will be the biggest thing to happen in the history of boxing to date."

Tarver, who beat Montell Griffin to win the 175-pound title Jones vacated, says Jones shouldn't be looking too far ahead.

"Why people don't give me a real chance in this match is beyond me," Tarver said. "This is a dangerous fight for Roy Jones. The risks outweigh the reward. Finally he's going to earn his money, every dime of it."

Realistically, there is little reward for Jones outside of a decent payday. He's fighting for a title he already gave up, and facing a guy who has been in only one title bout in his career.

But he didn't like Tarver's claims that Jones has been ducking a fight. And he wasn't happy when Tarver went to the Jones-Ruiz postfight news conference and yelled at Jones for avoiding him.

Jones (48-1, 38 knockouts) has been criticized before for fighting weak opponents and letting them go the distance. He says that won't happen with Tarver.

"I'm stopping him. I don't care what round it is, but I'm stopping him," Jones said.

Both fighters weighed in at the class limit of 175 pounds.

The bout is actually the second between Jones and Tarver, who met as 13-year-olds in the Sunshine State Games in Florida. Jones came away from that three-round amateur fight with a decision win.

There's a lot more at stake Saturday for Tarver, who gave up boxing only to return to the sport after watching Jones get robbed of the gold medal in the 1988 Olympics. Figuring he was as good as Jones, he began fighting again and won a bronze medal in the 1996 Games.

"When I laid eyes on him in Seoul, I knew that was my destiny," Tarver said. "I knew I was just as good as he was or better when we fought."

Tarver (21-1, 17 knockouts) is a lanky southpaw with good skills and a reach advantage over Jones. But most in boxing consider Jones the best of his time, a fighter with unlimited talent who isn't forced very often to use much of it.

Tarver says he will pressure Jones and not allow him to stay outside and use his boxing skills to pile up points the way he did against Ruiz.

"It will not be a cakewalk. You won't see Roy Jones on the outside prancing around," Tarver said. "That kind of fight I can guarantee you won't happen."

In the other title fight, Wright makes the fourth defense of his IBF 154-pound title against Hernandez, the No. 6-ranked contender. Wright, who lost a disputed decision to Fernando Vargas in 1999, has been trying to get boxers such as Vargas, Oscar De La Hoya and Shane Mosley to fight him.