Anastasia Dobromyslova injected Girl Power into the PartyPoker.com Grand Slam of Darts with a sensational victory over Vincent van der Voort.
The 25-year-old Russian produced the biggest ever win by a woman in a televised contest, edging out van der Voort 5-4 in a nine-leg thriller.
She hit back to level with a 121 finish after van der Voort led 3-1, and also took the deciding leg with a 100 checkout to ensure a winner-takes-all clash with Mark Webster on Tuesday.
"I'm on top of the world," said Dobromyslova, only the second woman to defeat a man on TV in recent years, after Deta Hedman in the 2005 UK Open.
"I'm really pleased a lady has won and pleased it's me. This year, I'm a different player to when I played in the Grand Slam in 2008.
"I feel more comfortable and that shows on stage - but I've not qualified yet and I've got to think of playing Mark Webster on Tuesday now."
Webster suffered the same fate as Dobromyslova 24 hours earlier when he took on reigning champion Phil Taylor later on Sunday evening, losing 5-0 as Taylor racked up a 105 average.
Taylor has now booked his place in the second round, while Mervyn King is also assured a last 16 spot following a 5-4 win over Steve Maish.
Maish led 3-1 after taking out finishes of 161 and 100, but King battled back to edge the win and a second successive victory.
Maish will take on Kirk Shepherd in the third round of group games on Tuesday, after the youngster overcame Darryl Fitton 5-3 with a strong display.
Tony O'Shea, the number eight seed, has one foot into the second round following his 5-2 defeat of Colin Osborne.
Colin Lloyd whitewashed Brian Woods 5-0 in the other Group B game and now needs to defeat O'Shea on Tuesday to progress.
Womens World Champion Francis Hoenselaar threatened another upset in Group D, when she led John Part 2-0 before succumbing to a 5-3 loss against the Canadian.
Part now needs to defeat Raymond van Barneveld in their final group game on Tuesday, after the Dutchman battled from 3-1 down to defeat Kevin Painter in a decider.
Groups E-H play their second matches on Monday night, with the games featuring BDO World Champion Ted Hankey's must-win contest with Wayne Mardle.
PartyPoker.com Grand Slam of Darts
Sunday Evening Results - Groups A-D
John Part 5-3 Francis Hoenselaar
Colin Lloyd 5-0 Brian Woods
Vincent van der Voort 4-5 Anastasia Dobromyslova
Darryl Fitton 3-5 Kirk Shepherd
Raymond van Barneveld 5-4 Kevin Painter
Phil Taylor 5-0 Mark Webster
Tony O'Shea 5-2 Colin Osborne
Mervyn King 5-4 Steve Maish
