ATLANTA — Boxer Paul Williams was paralyzed Sunday after being involved in a motorcycle crash in the Atlanta suburbs and doctors said it is unlikely he will continue his career, his manager said Monday.

"From the waist down, he has absolutely no movement. He's in very good spirits, though," George Peterson told The Associated Press from his home in Aiken, S.C. "He still believes he's going to fight again."

Williams, 30, severed his spinal cord after falling on his back and head when he was thrown from his motorcycle Sunday morning in Marietta, Ga., Peterson said. Williams has been listed in serious but stable condition on Monday at an undisclosed hospital, Peterson said.

The crash happened Sunday morning in Marietta after Williams tried to avoid another car in the next lane that was negotiating a curve and then had to maneuver to avoid an oncoming car. Williams was in the area to attend his brother's wedding Sunday afternoon, Peterson said.

"I know he's going to make a statement after surgery on Wednesday, because he's that kind of person," Peterson said. "He's 100 percent coherent and still has the will to want to get back on the motorcycle."

Williams was scheduled to fight Saul "Canelo" Alvarez on Sept. 15 in Las Vegas but that event has been canceled, Peterson said.

His longtime promoter, Dan Goossen, confirmed the cancellation of the fight on Monday evening.

"Right now, there's no thinking about any fights right now except for the fight that's facing Paul right now – to get movement back in his body and keep the movement that's above his waist," Goossen said.

Peterson said he continues to hope with Williams that the boxer's career isn't over.

"I want to think along with him, `cause I've seen him do things in his boxing career that shouldn't have happened," he said.

Williams is among the most versatile and unusual athletes in boxing, making him a highly undesirable opponent for the world's best fighters during his lengthy, successful career. He has competed effectively in an impressive three weight classes against much shorter foes, even comfortably making the 147-pound welterweight limit despite his lanky 6-foot-2 frame.

Williams won his first major welterweight title in July 2007 with a decision over Antonio Margarito. He struggled to land fights with the sport's biggest stars because of his pronounced size advantages, a high-volume punching rate and his relative anonymity, but was considered one of the world's top pound-for-pound stars.

He earned victories over Carlos Quintana, Winky Wright, Sergio Martinez and Kermit Cintron, but Martinez abruptly stopped Williams' rise in November 2010 with a second-round victory in their rematch. Williams ended up face-down on the canvas with his eyes wide open in perhaps the most spectacular knockout in recent boxing history.

Williams was unimpressive in his next two fights, but his bout with Alvarez – the popular young Mexican star – at Las Vegas' MGM Grand Garden was his return to the big time – and a chance to win Alvarez's WBC 154-pound belt.

"We want his fans to know he's going to be all right and he'll be back," Peterson said. "He said if he wasn't going to be boxing, he's going to be a stand-up comedian."