Berlin, Jun 17 (IANS): American tennis player Coco Gauff knocked out No 4 seed Karolina Pliskova 7-5, 6-4 in 1 hour and 37 minutes to reach the semifinals of the German Open, here on Friday.

Gauff had lost her only prior meeting against last year's Wimbledon runner-up Pliskova, and she had also lost her last four matches against players ranked inside the Top 10. But that all changed as World No. 13 fought off four set points in the first set en route to victory over seventh-ranked Pliskova.

At 5-4 in the opener, Pliskova ended a rally with a stunning forehand winner down the line to line up two set points. But Gauff used excellent serves and deft slices to ward off those two, as well as two more, before holding for 5-5 after a challenging 15-minute game.

Gauff's determination paid off immediately, as she broke Pliskova in the very next game with a backhand winner down the line. The U.S teenager kept the momentum at 6-5, serving out the set at love.

Czech Pliskova, who was playing her first match against a Top 20 player this season, started the second set with a 2-0 lead, but Gauff quickly pulled back on serve with a passing winner.

Another lengthy game at 4-4 went Gauff's way, as she converted her fourth break point of that game to earn a chance to serve out the win. The 18-year-old American took that opportunity with aplomb, slamming her fifth ace of the day to polish off the match.