What a day, eh? Two quarterfinals, two big upsets, with Belgium's Elise Mertens and Britain's Kyle Edmund advancing. 

This marks the first time there have been unseeded men's and women's semifinalists at the Australian Open since 1999 (Amelie Mauresmo; Tommy Haas, Thomas Enqvist, Nicolas Lapentti).

And there are still SIX spots to fill, with Hyeon Chung v Tennys Sandgren guaranteeing another unseeded player in the final four. 

We're going to take a brief break here at Tennis HQ, but we'll be back at 1900 AEDT for another big night session: Rafael Nadal v Marin Cilic and Carla Suarez Navarro v Caroline Wozniacki.