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 number 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.

World No. 1 Roger Federer advanced into his 34th consecutive Grand Slam quarter-final without touching a racquet on Monday when American Mardy Fish withdrew from their US Open match for health reasons.

The 31-year-old Swiss star, seeking his 18th Grand Slam title and sixth US Open crown, advanced into a last-eight matchup against Czech sixth seed Tomas Berdych, who dispatched Spanish 11th seed Nicolas Almagro 7-6 (7/4), 6-4, 6-1.

“I probably need to have something more than 100 percent,” said Berdych, who has lost 11 of 15 career meetings to top seed Federer.

The walkover stretched Federer’s record for consecutive quarter-final Grand Slam appearances in the Open era to 38, three shy of the record 41 achieved by American Jimmy Connors.

Federer, who won his 17th Grand Slam title in July at Wimbledon, has not dropped a set in the Flushing Meadows fortnight.

Fish missed two months of the season earlier this year because of a heart problem, being hospitalized after the Miami Masters event in March when his heart rate increased to three times its normal resting pace.

Fish, 30, then had a cardiac catheter ablation in Los Angeles on May 23 to address his heart condition.

Berdych, who took only two hours to reach his first US Open quarter-final, has won three of his past six meetings with Federer, including a US Open tuneup last year at Cincinnati and a 2010 Wimbledon quarter-final.

Berdych finally reached the last eight after 10 tries with his 200th career hardcourt triumph. He joined Petr Korda and Ivan Lendl as the only Czech men in the Open era to have reached the quarter-finals at all four Grand Slam events.

“I’m very happy that I can compete in all Grand Slams at least in quarter-finals. It helps my confidence,” Berdych said.

At last January’s Australian Open, Berdych was fuming at Almagro, accusing the Spaniard of hitting a ball at his face while he was at the net during a rally in a fourth-round match. The ball struck him in the arm.

Spectators booed Berdych for refusing to shake hands with the Spaniard after the match, but the Czech said Almagro’s apology was not enough to satisfy him.

Berdych dismissed the acrimonious incident this week as “nothing at all”, noting they have since split two ATP matches, although this was their first Grand Slam meeting since.

They clasped hands after Monday’s match at Louis Armstrong Stadium, Almagro flashing a quick smile at his conquerer as they met at the net.

Almagro, 27, figures to replace injured Rafael Nadal on the Spanish Davis Cup team that will host the United States next week in a semi-final tie. Almagro is unbeaten in four Cup singles matches so far this year.

Berdych, whose best Grand Slam result was a 2010 Wimbledon final loss to Nadal, improved to 7-3 lifetime against Almagro and snapped a five-game losing streak to top-20 rivals dating to a Rome victory over Almagro last May.

Berdych took three of the last four points to win the first-set tie-breaker, a forehand volley winner claiming the set after 48 minutes.

“It was really close, especially in the first set,” Berdych said. “It was a fight for every point. It was a tough match.”

Almagro had a break point in the fourth game of the second set but Berdych erased it with a 127 mph ace and then broke Almagro in the seventh game and held serve twice more to take the second set.

Berdych broke at love to begin the third set and again in the third and final games.