Coco Gauff produced a brilliant display to beat top seed Kiki Bertens in straight sets and reach the Linz Open semi-finals in Austria. The 15-year-old, who will break into the world's top 100 on the back of her run this week, beat world number eight Bertens 7-6(1) 6-4. Gauff is projected to rank 89th on Monday, although that will rise should she progress to the final. The American, who reached the second week at Wimbledon earlier this year, is now just two wins away from her first-ever WTA title having made her debut on Tour in March at the Miami Open. She only qualified for this week's tournament as a lucky loser after a late withdrawal from Maria Sakkari, but she now faces Andrea Petkovic for a place in the final. Petkovic needed just over an hour to beat Viktoria Kuzmova 6-4 6-1 earlier on Friday. Meanwhile, Jelena Ostapenko's impressive run continued as she beat Elena Rybakina 7-5 6-1. She faces Ekaterina Alexandrova, who brushed Kristina Mladenovich aside 6-2 6-4 to reach the semi-finals.