MELBOURNE (AP):

Asked what the future might hold for her young opponent, Venus Williams offered some heartfelt advice that could easily apply to her own career.

"Sky's the limit," said the 34-year-old Williams. "There is no limit on what you can achieve. No one can stop you."

"Sometimes you may not win every match, but there's a lot of them you can win," said the seven-time Grand Slam champion.

Williams did not win her quarter-final yesterday at the Australian Open. That honour went to 19-year-old Madison Keys, a composed and confident power hitter who might be the future of American women's tennis.

After beating Williams 6-3, 4-6, 6-4, Keys now faces her first Grand Slam semi-final against Venus's celebrated sister, Serena, who has already won 18 major titles.

For 10 days, Venus' impressive run at the Australian Open provided one of the tournament's feel-good story lines. It was the first time since 2010, that Williams, who has suffered from an auto-immune illness, had reached a Grand Slam quarter-final.

Some called it a comeback, or a late-career resurgence. For the first time in years, Williams did not face a single question in her post-match news conferences about retirement, so she did not have to reiterate that she plans to keep playing as long as she still enjoys it.

In her two decades on the tour, Williams has won 46 titles, including her most recent one earlier this year in Auckland.