In one of the most stunning upsets in recent boxing history, Baltimore's Hasim "The Rock" Rahman toppled world heavyweight champion Lennox Lewis last night.

His left eye swollen from an early hit by Lewis, Rahman suddenly landed a mighty right cross on Lewis' chin 2 minutes and 32 seconds into the fifth round. The stunning hit sent the champion to the canvas, and the fight was over.

To the cheers of a crowd of 5,000 at Carnival City Casino outside Johannesburg, Rahman was declared the new holder of the WBC and IBF heavyweight titles.

Before the fight, Lewis had predicted he would knock out Rahman by the fifth round.

Viewed as a low-risk assignment by Lewis, Rahman beat the odds and brought the heavyweight title back to the United States and, for the first time ever, to the city of Baltimore.

Rahman's manager, Stan Hoffman, said he planned to have Rahman fight next in South Africa within three months.

"I hope within three months we'll have a voluntary defense," said Hoffman. As for the site: "I owe it to the people of South Africa."

Although Lewis predicted he would knock out Rahman, the challenger's team had a plan of its own.

"We had a plan," Hoffman said. "The idea was to get Lewis comfortable. Draw him in. Draw him in. Make him feel very confident. And get close enough to throw the big right."

The strategy worked.

To the sounds of rap music, Rahman stepped into the ring wearing black and red trunks and headband, looking extremely confident.

Preceded by fireworks and a parade of Zulu dancers, Lewis, in white trunks with red trim, stepped into the ring to the sounds of a political tune in the Xhosa language called "Mandela bring us peace."

Rahman was the clear favorite as soon as he stepped into the ring.

In the first round, Rahman appeared to be the crowd favorite. Fans chanted "Hasim! Hasim!" as he made contact first. Lewis tried to connect with a left hook unsuccessfully.

The second round ended with both fighters not wanting to break it up. They spent the round trying to land big punches. Rahman threw a lot of body punches.

In the third, Lewis connected with a couple of lefts, but the fighters continued to get tied up. Rahman at one point got Lewis up against the ropes, throwing combinations at the champion's body.

In the fourth round, Lewis forced Rahman against the ropes. But to the cheers of the audience, the challenger fought back. With a few seconds left in the round, Rahman connected with a right and brought the crowd to its feet. "Hasim! Hasim" the crowd again cheered.

Lewis, 6-5, stepped into the ring at 253 pounds, his highest weight for a championship fight. But his 6-2, 237-pound challenger from Baltimore was at his lowest weight in recent years.

The British champion's extra pounds drew criticism last week from many boxing analysts who viewed them as a sign that Lewis was not taking this fight seriously enough. Yet Lewis, a former Olympic gold medalist with 38 wins, 1 loss and 29 knockouts to his credit, was the clear favorite.

He had defended his title three times since winning the WBA/IBF crowns from Evander Holyfield in 1999. Lewis' only defeat was in 1994, when Oliver McCall knocked him to the canvas in the second round.

Underdog Rahman, however, won over the hearts of South Africans for his unwavering confidence before the fight. With a record of 34 wins, 2 losses and 28 knockouts, he seemed to trust not just in his physical skills but also intangible strengths like his "heart."

Rahman, who first learned to box in the street before being directed to the gym eight years ago, won the World Boxing Union title in May 2000 in a seventh-round knockout of champion South African Corrie Sanders.

But along the way Rahman suffered losses in the two biggest bouts of his career. He was knocked out by Samoan David Tua in 1998, and knocked out of the ring completely by Russian Oleg Maskaev in 1999.

Altitude was expected to be a crucial factor in the fight. At 5,748 feet, the Johannesburg region of South Africa is known for its thin air. Rahman arrived nearly one month ago to acclimate to the challenging conditions.

Lewis flew in less than two weeks ago, raising questions about whether he would be in prime shape for the fight.

For Africa, the Lewis-Rahman fight marked the return of heavyweight championship boxing to the continent. Promoters dubbed the bout "Thunder in Africa" in their efforts to tap into memories of the legendary 1974 "Rumble in the Jungle" matchup between Muhammad Ali and George Foreman in Kinshasa, Zaire (now the Democratic Republic of Congo).

In that fight, underdog Ali won the title by knocking out Foreman in the eighth round.