ADELAIDE, South Africa, Jan 14, 2026 (BSS/AFP) - Defending Australian Open champion Madison Keys overcame some first-set serve wobbles to win her latest warm-up match for the opening Grand Slam of the year on Wednesday.

The 30-year-old American, who will be seeded ninth when the Australian Open begins on Sunday, beat Czech teenager Tereza Valentova 6-4, 6-1 at the Adelaide International.

Keys, who won in Adelaide last year before going on to lift her maiden major, served up seven double faults in the opening set against the 18-year-old.

She improved in the second, breaking twice and converting her third match point to reach the quarter-finals after an 85-minute workout on court.

"Experience helps get through the tricky moments," Keys said.

"I was able to take momentum in the second set and play really well. I had to raise my level. You have to take your chances on any opportunities you get."

World number 60 Valentova is one of a number of rising young talents on the women's circuit.

Keys said that facing the new generation was always a challenge.

"I have to lean on my experience a little bit. They are so young, have so much energy and are just so good. You expect them to play great tennis."

The American will face another teenager, 17th-ranked Victoria Mboko, in the last eight. The 18-year-old Canadian announced herself on the world stage last year by winning the WTA 1000 title in Montreal and the Hong Kong Open.

Keys began her 2026 Australian Open preparations last week in Brisbane, losing in the quarter-finals to world number one Aryna Sabalenka in a rematch of last year's Australian Open final.