ESPN Boxing

NEW YORK -- When he steps into the ring against Bernard Hopkins on Saturday, middleweight champion Kelly Pavlik will be fighting in his third weight class in as many bouts this year.

Pavlik fought as a super middleweight in his February rematch with Jermain Taylor before dropping back down to middleweight for his June defense against WBO mandatory Gary Lockett.

The obvious appeal of Saturday's encounter is that it matches a long-ruling middleweight champion (Hopkins) against the current one (Pavlik), but with a 170-pound contractual limit, the participants officially will be light heavyweights.

Since almost the dawn of boxing, men have tried to climb the same ladder, with varying degrees of success. More than a century ago, Bob Fitzsimmons, first a middleweight champion, went on to capture heavyweight and light heavyweight titles -- in that order, strangely enough.

A few 160-pound champions -- Dick Tiger in the late 1960s, Roy Jones Jr. and Reggie Johnson in a more contemporary era -- successfully made the transition, while others like Harry Greb, Mickey Walker and Sugar Ray Robinson found the leap from 160 to 175 to be more daunting than they had imagined.

What has proved to be rarer still is the middleweight who successfully has moved up to light heavyweight and then back down again. Robinson did it, but he never actually became a light heavyweight; he weighed 157 when he challenged Joey Maxim in 1952.

And while neither remained at 175 for long, when they met in their 1989 rematch at Caesars Palace, Sugar Ray Leonard and Thomas Hearns both were former light heavyweight champions.

Leonard's ascent through multiple divisions was relatively straightforward; he already had won welterweight and junior middleweight titles when his controversial decision over Marvelous Marvin Hagler added the WBC middleweight belt to his portfolio. For his next trick, he challenged WBC light heavyweight champion Donnie LaLonde in 1988 at a catchweight that allowed the WBC's newly created super middleweight title to be on the line in the same fight.

After stopping LaLonde to win both titles, Leonard never defended the light heavyweight title. He did, however, keep the 168-pound belt, meaning that it was on the line when he met Hearns in their unification fight in 1989.

Hearns' trajectory was more unique. Like Leonard's, his first two titles were at 147 and 154, but the light heavyweight title was his third. Two years after unsuccessfully challenging Hagler, Hearns stopped Dennis Andries to win the WBC light heavyweight championship. Like Leonard, he never defended it but instead fought Juan Domingo Roldan to win the vacant WBC middleweight title later in 1987. The Hit Man was upset by Iran Barkley in his first defense, but in 1988, with Leonard poised to win his fourth and fifth titles in the same night, Hearns was determined to beat his old rival to the punch and arranged to challenge Fulgencio Obelmejias for the WBA super middleweight title a few nights before Leonard fought LaLonde.

Unstoppable

TV lineup The schedule for the Top Rank-Golden Boy Promotions card Saturday night (HBO PPV, 9 ET) from Boardwalk Hall in Atlantic City, N.J.: • Light heavyweights: Kelly Pavlik (34-0, 30 KOs) vs. Bernard Hopkins (48-5-1, 32 KOs), 12 rounds • Featherweights: Steven Luevano (35-1-1, 15 KOs) vs. Billy Dib (21-0, 11 KOs), 12 rounds, for Luevano's title • Middleweights: Marco Antonio Rubio (42-4-1, 37 KOs) vs. Enrique Ornelas (28-4, 18 KOs), 12 rounds, title eliminator • Middleweights: Daniel Jacobs (10-0, 9 KOs) vs. Tyrone Watson (7-1, 3 KOs), 6 rounds

Obelmejias pulled out with an injury, but the fledgling WBO agreed to sanction a bout between Hearns and James Kinchen for its newly created super middleweight title.

Although he wobbled early, Hearns hung on (literally) to win, setting the stage for Leonard-Hearns II in 1989.

The result was a fight neither deserved to lose. Although Hearns scored two knockdowns, Leonard won more rounds, and after 12 rounds, the three judges split three ways on the verdict, resulting in a draw.

The examples of Leonard and Hearns notwithstanding, history suggests it is much easier for a middleweight to become a light heavyweight than vice versa. Pavlik, a strong betting favorite over Hopkins, will retain his title whether he wins or loses, but the question is: Will the 6-foot-2 middleweight champion ever truly be a middleweight again?

"Without question," Pavlik's career-long trainer Jack Loew said when the Pavlik-Hopkins tour hit New York on Tuesday. "Kelly went up to super middleweight for the Taylor rematch, but then when he fought Lockett in [June], it was one of the easiest transitions back to 160 he's ever had."

"I don't see it as a problem at all," Pavlik said. "Even earlier in my career, I often fought much higher [he was 169 for a 2005 fight, for instance, dropped 10 pounds for another two months later and knocked out both opponents]. In this day and age, when there's much more attention paid to nutrition and conditioning and fighters take better care of themselves between fights, I really don't think it's a factor."

Loew noted that Pavlik reported to camp for Hopkins weighing "around 175" and insisted Pavlik will have no trouble returning to middleweight -- if that indeed turns out to be where he fights next.

Should he beat Hopkins and Joe Calzaghe prevail in next month's fight against Jones ("And we're licking our chops just thinking about that," Loew said), a choice between that and a mandatory against the winner of the WBC eliminator between Marco Antonio Rubio and Enrique Ornelas on Saturday's undercard might be no choice at all.

"Of course it depends on what's there for us," Loew said. "That's why we're fighting Bernard in this one -- there was really no viable opponent at 160. Kelly has always said he wants to fight [IBF champion] Arthur Abraham to unify the titles, but Abraham [facing his own mandatory against Raul Marquez] wasn't available. If and when he is, Kelly would love to fight him, and trust me, he won't have any problem whatsoever making 160 to do it."

George Kimball, who writes for the Irish Times and Boxing Digest as well as ESPN.com, won the Nat Fleischer Award for Excellence in Boxing Journalism in 1985. He is the author of the widely acclaimed new book "Four Kings: Leonard, Hagler, Hearns, Duran and the Last Great Era of Boxing."