LAS VEGAS -- Roy Jones Jr. isn't a happy fighter.

A little more than a week before he fights Antonio Tarver for the light heavyweight titles he once held, Jones says he's still feeling the effects of losing enough weight to get down to 175 pounds.

"It's one of the worst times I ever had," Jones said. "You sacrifice so much you want to kill somebody."

Jones has good reason to be upset. For most of his career he had little trouble making weight as he won championships from middleweight to light heavyweight.

That changed, though, when he ventured into the heavyweight ranks in March, bulking up to 193 pounds to beat John Ruiz and win the WBA portion of the heavyweight title.

Now, he has to get back down to 175, and Jones said Wednesday it hasn't been easy. The most difficult time, he said, was getting back beneath 195 pounds, but it wasn't until last week that he began feeling comfortable at his lower weight again.

"I had to run more, diet more," Jones said. "You're hungry, thirsty half the time. You're mad. You start taking out your frustrations on everybody you come across."

That could be trouble for Tarver, who won the light heavyweight titles Jones vacated when he moved to heavyweight. The two meet Nov. 8 in a scheduled 12-round fight with the WBC and IBF 175-pound titles on the line.

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

Jones, who will decide what to do with his heavyweight title after facing Tarver, is fighting for the first time since he won an easy decision over Ruiz to become only the second light heavyweight champion to win a heavyweight title.

He's favored to beat Tarver in a fight that has become personal to both boxers and was nearly derailed because of an impasse over whether Tarver would enter the ring last as champions traditionally do.

"I'm going to utilize his big mouth for a big target all night," Jones said.

Tarver, a southpaw who beat Montell Griffin in April to win the vacated titles, is a 1996 Olympic bronze medalist who is 21-1 with 17 knockouts as a pro. He once sparred with Jones when both were 13-year-olds, and credits watching Jones getting robbed of a gold medal in Seoul with returning his interest to boxing.

Tarver claims Jones has been ducking him for three years and that beating him will bring some excitement back to boxing.

"I'm approachable, I'm fan friendly. I'm what the boxing world needs, a breath of fresh air," Tarver said. "My goal is not just to become a champion. I want to be a superstar in this game."