Melbourne: Elise Mertens became the first Belgian to reach the quarter-finals of the Australian Open since Kim Clijsters in 2012 with a straight sets win over Petra Martic on Sunday.
The unseeded world number 37 edged the big-serving Croat 7-6 (7/4), 7-5 in almost two hours of baseline war on Margaret Court Arena.
In-form Mertens is making her Australian Open main draw debut and is on an nine-match win streak after making a successful title defence in the warm-up event in Hobart just over a week ago.
"I've had an amazingly good start to the year," she said after having to grind out victory after leading 4-0 in the first set and being broken in the second when serving for the match for a first time.
She could next face another in-form player, fourth seed Elina Svitolina who won the Brisbane International warm-up.
The Ukrainian will first need to get through a late match against qualifier Denisa Allertova.
Mertens is in uncharted territory in her fifth appearance in the main draw of a Grand Slam.
She has only once before got past the opening round in a major, at Roland Garros last year when she reached the third round.