Iga Swiatek and Coco Gauff reached the semi-finals of the Adelaide International with contrasting victories in Thursday's play.
Reigning French Open champion Swiatek is through to the last four of a tournament for the first time since her success at Roland Garros, having spent just over an hour on court against Danielle Collins.
Swiatek had taken the opening set and was already 3-0 in up in the second when Collins was forced to retire due to a lower back issue.
The fifth seed will next take on Jil Teichmann, who failed to take any of the five match points that came her way during a dramatic second set tie-break with Anastasija Sevastova, though she eventually prevailed in the decider.
Teichmann staved off two opportunities for her opponent when serving at 4-5 in the third as she claimed three games in a row to triumph, a 6-4 6-7 (10-8) 7-5 victory coming after two hours and 57 minutes.
In the other half of the draw, Gauff had to fight hard to seal her progress, having been down a set and 4-2 to Shelby Rogers.
The 16-year-old, who came through qualifying, rallied to triumph 2-6 6-4 6-4 and reach the semis at a WTA 500 event for the first time.
"I didn't realise how much a role experience plays until I started playing some players who are a lot older than me and they know what to do," Gauff said, per the WTA Tour's website.
"Even when it comes to the little mind games and all that, they know what to do in those moments. So I'm just learning and picking up a few tricks and as I go."
Gauff, who has won all three of her matches in the main draw via a deciding set, will go up against second seed Belinda Bencic, the Swiss having swept aside Storm Sanders in straight sets.