MELBOURNE, Australia - Maria Sakkari roared into the second week of a major tournament for the first time in her career, defeating No.10 seed Madison Keys, 6-4, 6-4, to reach the fourth round of the Australian Open.

"I have been struggling a lot at every Grand Slam," she said during her on-court interview. "I was getting stuck at the third round, so I'm so happy to be through to the fourth round! It was a great day for me, and a great crowd."

Sakkari was playing a Grand Slam third round for the eighth time in her career, and finally broke through in emphatic fashion, booking a Round of 16 clash with 2019 runner-up Petra Kvitova after one hour and 15 minutes on Margaret Court Arena.

Sakkari and Keys were facing off for the first time, and while the Greek No.1 had enjoyed a solid start to the 2020 season - pushing Naomi Osaka to three sets at the Brisbane International - Keys had been in stellar form, finishing runner-up to Karolina Pliskova at that same event.

Neither had dropped a set en route to the third round, and the two were set to do battle with their contrasting styles. Sakkari's heavy topspin proved potent early as she scored the first break of the match and raced ahead 5-2 in the opening set.

Keys, a former semifinalist in Melbourne who won the biggest title of her career last summer at the Western & Southern Open, did her best to reduce the deficit, breaking Sakkari as she served for the set and put down a decisive love service hold to narrow the gap.

Sakkari responded with aplomb, earning two set points in her second opportunity to serve out the set, moving ahead on her third set point.

The second set saw the American nonetheless capitalize on her late momentum, moving ahead 4-2 as a deciding set seemed likely. 

Undaunted, Sakkari broke straight back and rolled through the final four games of the match, saving a break point in the final game to secure victory to the delight of the many Greek fans in the crowd.

In all, Sakkari hit nine errors to 21 unforced errors - half of Keys' totals, 17 and 40, respectively - and won 15 of 21 points played on the American's serve, which she broke broke four times throughout the match.

Kvitova stands between Sakkari and a first Grand Slam quarterfinal. The duo last played in Cincinnati back in August, where the 24-year-old won in three hard-fought sets.

"It'll be another tough match and another big hitter. We've played multiple times. I really want to enjoy my day today and not think about my next round, so I'll start thinking about my next match on Sunday morning. I just want to enjoy Melbourne and all of the people here."

2020 Australian Open highlights: Sakkari sweeps past Keys