SAN DIEGO (CNS) - Heavyweight boxer Ken Norton Sr., who stunned the sports world 40 years ago by defeating Muhammad Ali at the San Diego Sports Arena, died Wednesday at the age of 70.

Norton, who broke Ali's jaw and won a split decision in the San Diego fight, won subsequent rematches, one of which was at the Forum in Inglewood.

Family and friends said Norton, who died in a hospice facility in Las Vegas, had been in poor health for several years following a series of strokes, according to reports.

Norton began boxing at Camp Pendleton in northern San Diego County and turned professional in 1967, according to the San Diego Hall of Champions.

He compiled a 27-1 record before the first fight with Ali, which took place on March 31, 1973. He broke Ali's jaw in the second round, but Ali refused his trainer's pleas to come out of the fight. The match continued, and Norton was afterward declared the winner.

Norton, whose son Ken Jr. was a linebacker in the NFL and a star at UCLA, retired in 1981 with a 42-7-1 record.