Teenager Amanda Anisimova put in one of the most impressive performances in recent French Open history on Thursday as she stunned defending champion Simona Halep 6-2 6-4 to reach the semi-finals. Anisimova has been one of the revelations of the tournament so far, taking advantage of seeds falling around her to reach the last eight, but Halep represented a step up in terms of what she had faced in Paris thus far. However the teenager showed no signs of nerves during her first appearance on Court Philippe Chatrier as she dismantled the reigning champion in the opening set. Her forehand, already a well-documented weapon, was at its brilliant best but it was her backhand that really impressed, as Halep tried to target it only to discover there were no weaknesses to be found. In a devastating period from 2-2, Anisimova won seven games in a row to claim the opening set and then move 3-0 up in the second. In the fifth game of the second set Halep nearly pulled out the break on a number of occasions, with a couple of errors creeping into her opponentвЂ™s game. However a quite sensational rally was won by Anisimova as she eventually held to retain her three-game lead. Yet a crack had appeared and Halep pressed home the advantage. She broke twice to put increased pressure on the teenager, with Anisimova visibly stressed on court. The American regrouped however in a crucial hold before then forcing errors from Halep to break and secure victory. Anisimova, who is yet to drop a set at Roland Garros this year, will now face Australian Ash Barty for a place in the final. Speaking after the match, she said: "I was trying to be [calm], but my hands were shaking, especially in the second set when I had that lead, 4-1. "Every time I was getting closer and closer, it was getting tougher. I was really nervous, I'm just happy I got to close it off." Anisimova also explained how she targeted Halep's backhand in her approach to the match. "The biggest thing I was remembering was, because I was trying to hit my backhand down the line like her, I knew everytime she was going to hit her backhand down the line. "I was trying to hit like her but then I had a gameplan against her." Her opponent said she would now focus on preparing for Wimbledon. "Now it's a little bit easier because I have few days off, and then I can go and train on grass courts," Halep told reporters. "It's maybe the seventh year I do these things, coming from clay to grass court. I got used to it." Last year, she did not play any grasscourt tournament between the French Open and Wimbledon, where her best result remains her run to the semi-finals in 2014. Halep admitted the stress that comes with being the defending champion played a part in her performance after she lost seven games in a row to go from 2-2 in the first set to 6-2 3-0 down in the second. "Stressed because I felt that I'm playing well, and maybe my expectations for myself were big today," she explained. "Maybe I couldn't handle the tension in my body so I couldn't play my best and I couldn't move at my best level." The 27-year-old, however, was gracious in defeat, predicting a bright future for her opponent. "Today I felt how she's playing, because before, I had never played against her," she said. "I couldn't say something more. But I think she has a chance and she will be in the top soon, because she has the game. She sees the game, has the attitude, good attitude, so I think she's a great player." Halep said she would not dwell on the disappointment. "I think it will help me for the future tournaments. I'm not negative now. I'm not very disappointed," said Halep. "It's normal to be a little bit disappointed after a loss, but I feel okay, and I'm looking forward to a new day tomorrow. "Actually, a few days off first."