New York - Serb 12th seed Ana Ivanovic reached her first Grand Slam quarter-final in four years, and first ever at the US Open, when she defeated Bulgaria's Tsvetana Pironkova 6-0, 6-4 on Monday.
The 24-year-old, whose last major quarter-final came on the way to her one and only Grand Slam triumph at the 2008 French Open, swept through the first set in just 23 minutes, firing 13 winners and giving up just 11 points.
Pironkova, the world No 55 who became the first Bulgarian to make a Grand Slam semi-final when she charged into the last four at Wimbledon in 2010, was the first woman from her country to make the last 16 in New York since 1994.
But her challenge was restricted by a neck injury and she twice needed treatment, including a medical time-out at the end of the first set.
She battled gamely in the second set, breaking Ivanovic twice, including the ninth game when the former world number one was serving for the match.
But the Serb hit back immediately for victory in the 10th game with the match's 10th break of serve in the 16 games played.
"I hardly made any mistakes in the first set but she is a tough opponent and I knew she would come back in the second set," said Ivanovic after her 71-minute win, where she finished with 28 winners and 21 unforced errors.
"It's amazing to be in my first quarter-final at the US Open."
Ivanovic will next face either three-time champion Serena Williams, who is targeting a 34th career Grand Slam quarter-final spot, or Czech world number 82 Andrea Hlavackova.
Olympic and Wimbledon champion Williams has a lifetime record in New York of 61 wins against just nine defeats.
Hlavackova, 26, is making her US Open main draw debut having lost five times in qualifying and will be playing in her first last-16 match at a major.
But she has tasted Grand Slam success, teaming with compatriot Lucie Hradecka to win the 2011 French Open women's doubles.
Ivanovic has lost all three meetings with Williams, failing to win a set. Two of those defeats came at the US Open in 2006 and 2011.
She has never faced Hlavackova.
German sixth seed Angelique Kerber, a semi-finalist in 2011, faces Italian 10th seed Sara Errani, the French Open runner-up.
Errani defeated Kerber, who has a season-leading 56 wins in 2012, in the quarter-finals in Paris on her way to the final in June.
The winner of that tie will face either Polish second seed Agnieszka Radwanska, who has equalled her best performance in New York of runs to the last-16 in 2007 and 2008, or Italian 19th seed Roberta Vinci.
Radwanska has won all of her four previous meetings with the 29-year-old Vinci who had made the last-16 for the first time.