A South African judge sentenced retired doubles tennis champion Bob Hewitt to six years in prison for rape and sexual assault on Monday.

Judge Bert Bam sentenced Hewitt to eight years in jail for two counts of rape of minors, with two years suspended. He also sentenced Hewitt to two years in prison for a third charge of sexual assault.

The three sentences will be served at the same time, meaning Hewitt, 75, should spend up to six years in prison, said Bam.

The seriousness of the crimes and the prevalence of sexual violence in South Africa, had to be considered, the judge told the courtroom in the country's capital, Pretoria. The judge cited previous cases in which perpetrators have been sentenced to life for rape, especially when the victims were children.

Australian-born Hewitt has denied the charges.  He won 15 Grand Slam doubles and mixed doubles titles at all four Grand Slam events between 1963 and 1979. He was in the International Tennis Hall of Fame but was suspended indefinitely after an investigation.

Hewitt's age was considered during the sentencing, but so was the age of his accusers who were minors when the assaults allegedly took place in the 1980s and 1990s, the judge said. South Africa does not have a statute of limitations for rape.

"No rapist and violator of children should be allowed to hide behind his age, medical condition and, or personal circumstances to escape custodial sentence," said Bam. The judge also ordered Hewitt to pay about $8,500 to state-run campaigns against sexual violence.

Before the judge ruled, Hewitt testified that he was in poor health. A heart condition, a stroke, and two artificial knees mean that Hewitt can "barely put his left foot before his right foot," his lawyer Terry Price said at the sentencing hearing.

The judge extended Hewitt's bail for another day, to allow his defense lawyers to appeal the decision. Hewitt's defense team said they plan to appeal the conviction and the sentencing.