MELBOURNE, Jan. 27 -- Jannik Sinner powered into the Australian Open quarter-finals on Monday, while defending women's champion Madison Keys crashed out, as Melbourne braced for a forecast 45C heatwave.

Read More: Keys dumped out in last 16 as Melbourne braces for heatwave

Sinner, recovering from cramps in his third-round match, defeated fellow Italian and close friend Luciano Darderi 6-1, 6-3, 7-6 (7/2) to book his ninth consecutive Grand Slam quarter-final. Playing in the shade at Margaret Court Arena, Sinner hit 19 aces and said his physical condition held up well despite the heat. He will next face American eighth seed Ben Shelton, who defeated Casper Ruud in four sets, seeking revenge for last year's semi-final loss to the Italian....