LAS VEGAS, OCT. 29 -- Thomas Hearns made boxing history tonight with a fourth-round knockout of Juan Domingo Roldan to win the vacant World Boxing Council middleweight championship.

The victory made Hearns the first fighter ever to win titles in four weight classes.

Hearns finished the fight with a right to Roldan's head that dropped him face down in the middle of the ring. The Argentina native rolled over on his back at the count of nine and was counted out at 2:01 of the round.

Immediately after the fight Hearns said to Marvelous Marvin Hagler, who was at ringside as a television commentator, "I hope we can get together and do it again."

Hagler, the former undisputed middleweight champion who knocked out Hearns in the third round in 1985, said, "I'm still evaluating the situation."

Then Hagler, who was upset by Sugar Ray Leonard in April, added: "The only reason I would come out of retirement would be Ray."

Leonard said he will not fight again. Leonard is the only other man to defeat Hearns, in the 14th round for the undisputed welterweight title in 1981.

But this 61-degree night belonged to Hearns.

"I'm happy I've done something no other man has done," he said.

The scheduled 12-round fight before about 11,000 spectators outdoors at the Las Vegas Hilton was a slugfest from the opening bell.

The 29-year-old Hearns knocked down Roldan twice in the first round and put him down again in the second.

But the 30-year-old Roldan kept fighting back and hurt Hearns on a couple of occasions.

"I want to put on a heck of a show and prove to the world I am a great champion," Hearns said before the fight.

He, indeed, put on a heck of a show.

With Hagler and Leonard watching at ringside, Hearns knocked down Roldan in the opening round with two rights to the head. Roldan got up at three and took a mandatory eight-count.

A short time later, Roldan hurt Hearns with a right to the head that made Hearns clinch.

With the round nearing its end, Hearns speared Roldan with a couple of lefts to the face. As Roldan moved backward, Hearns dropped him with a right to the jaw.

The bell rang about the same time Roldan hit the floor. Roldan struggled up at seven and wandered to his corner. The bell cannot save a fighter who has been knocked down except in the last round.

The 5-foot-7 Roldan, who weighed 159 1/2 pounds, came charging out in the second round and got caught with a left hook 20 seconds into the round that put him down again. He got up immediately, took an eight-count and spent the rest of the round charging after Hearns, who hit him with jabs and hooks.

Roldan's best round was the third, when a right-left-right to the head hurt Hearns (159 1/2 pounds). Roldan landed some other good punches to Hearns' head in the round, but suffered a bloody nose.

"I was pretty nervous," Hearns said. "I'm not used to getting hit and getting hurt.

"I thought, 'This one can't slip by me.' "

Twenty seconds into the fourth round, Roldan wobbled Hearns with a hook, but Hearns grabbed and held. A minute into the round, Hearns hurt Roldan with a right hand, and then, less than a minute later, he finished the fight with a right.

Hearns previously held the World Boxing Association welterweight title, the WBC super welterweight title and the WBC light heavyweight title. He weighed 173 3/4 pounds when he won the light heavyweight title in his previous fight, March 7, with a 10-round knockout of Dennis Andries.

Hearns was the fourth man to attempt to win a fourth crown. The three who failed were Henry Armstrong, who fought a 10-round draw in a bid for the middleweight title in 1940; Alexis Arguello, who was knocked out by Aaron Pryor in two bids for the WBA junior welterweight title in 1982-83, and Roberto Duran, who lost a decision to Hagler in 1983.

There have been 10 men to win three titles.

Hearns, who earned $1.1 million, boosted his record to 45-2 with 38 knockouts. Roldan, whose purse was $250,000, came away from his second middleweight title bid with a 63-4-2 record with 41 knockouts. He was the WBC's No. 2 contender and the WBA's No. 1 contender.

In a preliminary match, unheralded Charles Williams survived two early knockdowns and rallied to stop champion Bobby Czyz after nine rounds and capture the International Boxing Federation light heavyweight title.

Williams, a 2-to-1 underdog, pounded Czyz almost at will from the third round on to score the upset victory in the scheduled 15-round fight.

In another match, Michael Nunn, often criticized for a lack of punching power, won the vacant North American Boxing Federation middleweight title with a fourth-round knockout of Darnell Knox.