Iga Swiatek was dumped out of Wimbledon in straight sets on Saturday by French veteran Alize Cornet, ending the world number one's 37-match winning streak.

Cornet, ranked 37, took advantage of an error-strewn performance from her Polish opponent to win 6-4, 6-2 on Court 1 in their third-round tie.

Swiatek made a total of 33 unforced errors in an uncharacteristically sloppy display, compared with just seven by Cornet.

In reaching the fourth round, the French player matches her run at Wimbledon in 2014, when she beat Serena Williams in the third round.

"I have no words right now," she said. "It reminds me of the time I beat Serena on the same court eight years ago exactly. This court is a lucky charm for me."

Cornet said she felt Swiatek could be vulnerable on grass after pulling off the biggest shock at Wimbledon so far.

The 32-year-old reached a career milestone by defeating former number one Simona Halep to advance to her first major quarter-final at the Australian Open earlier this year.

"I'm like good wine," said Cornet, who is contesting her 62nd consecutive Slam, matching Ai Sugiyama's record.

"In France good wine always ages well, that's what's happened to me. It's unreal -- I'm playing one of the best seasons of my career."

Top seed Swiatek was on the back foot right from the start of the match, broken in her first two service games, and could not get back on level terms.

The 21-year-old broke at her first opportunity in the second set but Cornet broke back immediately, winning the last six games of the 93-minute match.

Swiatek had not lost a match since her defeat to Jelena Ostapenko in February in Dubai, winning her past six tournaments, including the French Open.

Though she had looked unbeatable on hard courts and clay, she had admitted she was on a learning curve on grass.

She was made to battle hard in the second round to defeat lucky loser Lesley Pattinama Kerkhove in three sets.

With her loss to Cornet, Swiatek still has yet to beat a top-50 player on grass.

Cornet will face Australia's Ajla Tomljanovic for a place in the quarter-finals.

Meanwhile, Amanda Anisimova came from behind to beat 11th seed Coco Gauff 6-7 (4/7), 6-2, 6-1 in an all-American clash on Wimbledon's Centre Court.

French Open finalist Gauff took the first set after a tie-break but was broken three times in the second set as the 20th seed levelled the match.

A break in the fourth game of the decider put Anisimova in the box seat and she swept into a 5-1 lead with another break.

The 20-year-old served out to love to set up a fourth-round match against Serena Williams's conqueror Harmony Tan, who defeated British wild card Katie Boulter earlier on Saturday. (AFP)