MADRID, Spain - No.9 seed Sloane Stephens aced an early test at the Mutua Madrid Open, seeing off former French Open finalist Sam Stosur in straight sets to reach the third round.

Stosur came into the matchup with a 2-1 lead over the American, with wins in both of their previous encounters on clay, and bidding to become the fourth player to win 20 matches in Madrid.

But the American had other plans, needing just over an hour and 15 minutes to see off Stosur and notch the comfortable, 6-1, 6-3 win.

Read more: Martina Navratilova: Now Stephens must do it outside the US

“To just be outside of the United States and still get a win is incredible,” Stephens said afterwards. “I’m super pumped that it’s here in Madrid, and getting the clay court season started pretty well.

“I think I played really well and super consistent, I competed very well so I’m pleased with that.”

The Aussie managed to hold her serve after a battle in the opening game, but it was one-way traffic from there as Stephens roared to life. She reeled off the next six games in a row - keeping Stosur under pressure and covering the court to retrieve every ball - and took the opening set in a comfortable 39 minutes

Stosur finally shook off her service woes in the second set, and the pair were quite even during the opening exchanges with the first five games going comfortably to the server. But Stephens raised her level once again to put Stosur under pressure, earning two break chances at 3-3 before finally breaking through late in the set at 5-3 before serving out the match.

Stephens outgunned the Aussie with 22 winners against 11 from Stosur, and 20 unforced error to her opponent’s 28. But it was her strong serving that made the difference in the match - she struck a fearsome 88% of first serves, winning 78% and 60% of second serves. As a result, she didn’t face a single break point across both sets.

With the victory, Stephens improves her post-Australian Open win-loss record to 13-3. She’ll take on the winner between the resurgent Victoria Azarenka and No.6 seed Karolina Pliskova, Stuttgart champion, in the third round.