SINGAPORE - New mom Serena Williams will lack some of her trademark intensity and intimidation when she returns to tennis, US great Chris Evert said on Tuesday, warning that the 23-time Grand Slam champion might find her comeback tough.

Williams, who gave birth to a daughter in September, has said she's planning to defend her title at the Australian Open in January.

But Evert said standards in women's tennis have risen this year since Williams stepped off the tour, warning that the 36-year-old would be returning to a more competitive environment.