The quarterfinals are underway at Melbourne Park, as rumours abound about Jannik Sinner's health ahead of his clash with Alex de Minaur. Follow live.

American Danielle Collins is out of the Australian Open following a straight-sets defeat by fellow countrywoman Madison Keys.

As much as any top player, Sinner has been able to expose De Minaur’s lack of first-strike weaponry. The Aussie’s strength is his scrambling and counterpunching, but Sinner serves too well, hits too hard, places the ball too precisely for his defense to be effective. De Minaur hasn’t found a way to hurt, rattle, of disrupt him.

The American rallied from a set down to reach the last four in Melbourne for the third time, and will face No. 2 seed Iga Swiatek next.

World tennis No.1 Jannik Sinner is reportedly seriously ill with pneumonia, ahead of his crucial clash against Alex de Minaur.

Lorenzo Sonego will take on American Ben Shelton in the other men’s quarter-final on Jan 22. Read more at straitstimes.com.

The Australian Open quarter-finals are heating up as Jannik Sinner, battling illness, faces Australia's Alex De Minaur. Meanwhile, Iga Swiatek enters her match free of doping appeals. Experienced players Madison Keys and Elina Svitolina also showcase their adaptability in women's top matches.

Top seed Jannik Sinner v Alex de Minaur Ben Shelton beats Lorenzo Sonego 6-4 7-5 4-6 7-6 (7-4) to reach semi-finals Iga Swiatek drops just three games on way to last four Swiatek will play Madison Keys,

Alex de Minaur has given a cheeky sledge to his fiancee Katie Boulter about their wedding ahead of the biggest match of his career. Welcome to news.com.au’s live coverage of Day 11 of the Australian Open.

Alex de Minaur is through to the quarterfinals of the Australian Open for the first time, defeating American giant-killer Alex Michelsen.

That man was Novak Djokovic, the 10-time Australian Open champion, who got lucky to snare a set. They met only once more last year - the Shanghai final - and Sinner did the legend over again. That is the quality of the player de Minaur was trying to take down.