World No.2 Simona Halep and two-time champion Venus Williams tumbled out of the US Open on Friday, but Maria Sharapova bucked the upset trend that rocked the women’s draw.

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.

“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.

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).

At the other end of the age spectrum, Swiss 17-year-old Belinda Bencic toppled sixth-seeded German Angelique Kerber 6-1 7-5.

Bencic, the 2013 Wimbledon and French Open junior champion, now ranked 58th in the world, earned a meeting with former world No.1 Jelena Jankovic, a 6-1 6-0 winner over Sweden’s Johanna Larsson.

“It’s amazing that after last year I played juniors here, and this year I’m in the fourth round,” Bencic said.

The last grand slam of the year has now lost four of its top 10 women’s seeds, after the second-round departures of Agnieszka Radwanska and Ana Ivanovic.

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.

Sharapova found herself in a power struggle, but emerged with a 6-2 6-4 victory over German 26th seed Sabine Lisicki in a match which finished after midnight.

Both women had more unforced errors than winners – Sharapova by 32 to 20.

In a match that saw nine breaks of serve, Sharapova broke Lisicki in the final game to clinch the win when the German fired a forehand out on Sharapova’s third match point.

“It was a really tough opponent I had today, a very aggressive, big server,” Sharapova said.

“I just tried to concentrate on my return, I wasn’t serving as well as I wanted to.”

China’s Peng Shuai, showing no sign of a let-down after her second-round win over Radwanska, dispatched another seeded player in No.28 Roberta Vinci 6-4, 6-3.

She set up a meeting with 14th-seeded Czech Lucie Safarova, a 6-3 6-7 (5-7) 6-4 winner over France’s Alize Cornet.