Rebeka Masarova pulled off a huge shock as she stunned second seed Jelena Jankovic to claim victory in her WTA main draw debut at the Ladies Championship Gstaad.
The 16-year-old was handed a tough assignment having been pitted against Jankovic after receiving a wildcard into the event.
But Masarova was undaunted by the prospect of facing the former world number one and continued a superb year that has seen her reach the win the girls' singles French Open and reach the last four of the Australian Open at the junior level with an incredible victory.
Jankovic appeared in control after taking the first set in commanding fashion, but Masarova fought back superbly to progress to the second round 1-6 6-4 6-2.
"I feel amazing," Masarova said after the match. "I prepared so well mentally and physically for this. I was so happy to play this match; I knew it'd be a good experience, but I wanted to win, and I'm glad I did.
"I resolved not to make too many mistakes, and was focused on what I had to do. I realised what she was doing to me; she was playing a lot to my backhand, and I had to play to her forehand.
"It wasn't about winning the point anymore, it was about not missing. But when I had the opportunity to make a point, I did."
Masarova's Swiss compatriot Viktorija Golubic is also through after completing her match with seventh seed Mona Barthel that had been interrupted by rain on Wednesday. Golubic won 2-6 6-1 7-5.
There was no such luck for fellow home hope Stefanie Voegele, with Carina Witthoeft claiming a 6-4 4-6 6-1 triumph in a match that had also been hampered by the elements.
Katerina Siniakova denied another Swiss a place in round two by beating wildcard Patty Schnyder 2-6 7-5 6-4.