Serena Williams faced her first real test at this year’s Australian Open and emerged with a 6-1, 4-6, 6-4 victory over No. 1-ranked Simona Halep to reach the quarterfinals.

It was a back-and-forth match filled with momentum swings and terrific play by both.

Williams gained control for good after saving three break points in a monumental game to hold for 3-all in the third set. She then broke for a 4-3 lead and finally was on her way.

The 37-year-old American is trying to win an eighth championship at Melbourne Park and record-tying 24th Grand Slam title overall.

Williams next meets 2016 U.S. Open runner-up Karolina Pliskova.