NEW YORK (AFP) - The US Open women's draw was blown open Friday as world number two Simona Halep, sixth seed Angelique Kerber and two-time champion Venus Williams tumbled out of the third round.
Two players at opposite ends of the tennis age spectrum authored the upsets of the day.
Croatian Mirjana Lucic-Baroni, a former phenom now a 32-year-old veteran who had to fight through qualifying, shocked second-seeded Halep, the French Open runner-up, 7-6 (8/6), 6-2.
And 17-year-old Swiss Belinda Bencic toppled Germany's Kerber 6-1, 7-5.
The reward for the 121st-ranked Lucic-Baroni is a fourth-round meeting with 13th-seeded Italian Sara Errani, who thwarted Williams 6-0, 0-6, 7-6 (7/5).
"It's incredible, amazing, I feel goofy," said Lucic-Baroni, who reached a Grand Slam fourth round for the first time since making it to the 1999 Wimbledon semi-finals as a 17-year-old.
Her life went into freefall after she revealed she was abused by her father, Marinko, and in recent seasons her career has been a struggle to support herself, train and find a way to re-establish herself on tour.
"Every painful moment has been worth it," said Lucic-Baroni, who rallied from 2-5 down to steal the first set then dominated in the second - sealing the match with back-to-back aces.
"I knew what I had to do and I was able to do it," said Lucic-Baroni, who broke down in tears later reflecting on her journey.
"I worked so hard for this."
Bencic, the 2013 Wimbledon and French Open junior champion, now ranked 58th in the world, earned a meeting with former world number one Jelena Jankovic for a place in the quarter-finals.
After dropping the lopsided first set, Kerber appeared poised to knot the match, but she couldn't convert three set points.
Bencic, coached by former Swiss great Martina Hingis' mother Melanie Molitor, seized her chance.
"It's amazing that after last year I played juniors here, and this year I'm in the fourth round," Bencic said. "So it's incredible."
The last Grand Slam of the year has now lost four of it's top 10 women's seeds, after the second-round departures of Agnieszka Radwanska and Ana Ivanovic.
Former champion and fifth seed Maria Sharapova was trying to buck the upset trend later Friday when she took on big-hitting German Sabine Lisicki under the floodlights on Arthur Ashe Stadium court.
Before that, men's second seed Roger Federer was to resume his quest for a sixth US Open title against big-serving Australian Sam Groth.
Errani's triumph over 19th-seeded Williams wasn't strictly speaking an upset, but the 13th-seeded Italian had to dig deep to notch her first career victory over the American after three defeats.
"I know that was a really tough match, even if I won the first set 6-0 she's an amazing player," Errani said.
And as she expected, five-time Grand Slam champion Williams battled back, racing through the second set to set up a third that turned into a slugfest.
Williams twice came back from a break down in the third, then broke Errani to serve for the match at 5-3.
She couldn't hang on, however, surrendering her serve as they battled to the tiebreaker, in which Errani took a 5-2 lead only for Williams to battle back to 5-5 before at last succumbing.
Errani was infected by the electric atmosphere in the Ashe stadium, even though she knew the frantic fans were for her opponent.
"To go 5-all in the tiebreak I heard the crowd," she said. "Never hear the crowd like that strong. I was shaking for the crowd. Was unbelievable good. I think I will remember forever that moment."
China's Peng Shuai, showing no sign of a let-down after her second-round win over Radwanska, dispatched another seeded player in number 28 Roberta Vinci 6-4, 6-3.
Ninth-seeded Jankovic, whose only Grand Slam final appearance was a runner-up finish at Flushing Meadows in 2008, was never in danger in a 6-1, 6-0 victory over Sweden's Johanna Larsson.
The surprises on the women's side overshadowed men's second-round action.
Fourth-seeded David Ferrer reached the third round without lifting his racquet when unpredictable Aussie Bernard Tomic withdrew with a hip injury.
Wimbledon semi-finalist Grigor Dimitrov of Bulgaria continued his best-ever US Open with a 6-1, 6-2, 6-2 victory over Dudi Sela, improving his career record against the Israeli to 3-0.
Croatia's 14th-seeded Marin Cilic, 18th seed Kevin Anderson of South Africa, 19th seed Feliciano Lopez and 20th seed Gael Monfils all advanced on cue.
Cilic belted 37 winners in a 7-6 (7/2), 6-2, 6-4 victory over qualifier Illya Marchenko to set up a meeting with Anderson, who knocked out Jerzy Janowicz 6-7 (6/8), 6-2, 6-1, 6-3.
The two last met in the ATP Delray Beach final, where Cilic grabbed one of his two titles of 2014.