Defending champion bows out in New York as Serena eases into semis.
The US Open title defence of Sloane Stephens collapsed in a 6-2, 6-3 heap on Tuesday night, with the American knocked out by Anastasija Sevastova.
The Latvian becomes the first from her nation to get this far at Flushing Meadows.
Meanwhile, Serena Williams rallied to get past Czech eighth seed Karolina Pliskova 6-4 6-3.
Williams is looking for an eighth New York trophy and her first since giving birth a year ago. Another win would put in 36-year-old into the record books by duplicating the all-time best total of 24 grand Slam singles crowns.
Pliskova got away to 3-1 in the opening set in hothouse conditions but was reeled in by Williams to take the opener with a sweep of the last four games.
She reversed the scenario in the second set by taking a 4-0 margin on her way into the semi-finals on Tuesday on the back of a 13th ace.
“I really feel like right now I’m playing free. I was having a baby this time last year so I have nothing to prove.”
“When I get to a Grand Slam, I feel I want to play really hard. I want to do really well. I love this game, Williams said after taking revenge for a loss to Pliskova here two years ago in the semis.
Fellow American Stephens went down on another heatwave day of 33 Celsius temperatures at the final Grand Slam of the season as Sevastova revered the result of a loss she took to the American last month in the Montreal quarters.
“It was very physical today,” Sevastova said as she played in her third consecutive quarter-final here. “It was so hot here in the stadium.
“We showed nerves in the end, but that’s normal — it’s for the semi-finals of the US Open. I just stuck to my game plan and took
my chances. I’m so happy.”
Stephens, 25, went down in 83 minutes, missing her opportunities on her first seven break points before finally connecting in the second set on an eighth chance.
Florida-based Stephens failed to back up the break against a player who missed a combined total of nearly two season due to injury from 2013, making a return to the sport in 2015 after a hasty retirement from the game.
“It was an amazing journey, this 3, 4 years…You can’t believe, yeah. So after I stop at some point I will look at it and I will be proud of myself, for sure,” she said.
Sevastova, saved seven of the nine break points she faced in the clash on Ashe.
Stephens admitted she produced a poor effort when it counted the most and was caught out by drop shots from the Latvian on numerous occasions.
“I just really couldn’t get anything to connect. Even when I did have my break opportunities, I just wasn’t playing the points well at all.
“It was a really tough day. The heat doesn’t make it any more fun.”
The winner said she took advantage of a lack of energy from the Stephens side of the net in producing a Grand Slam career best.
“I saw that she was struggling. I was struggling also a little bit, but I didn’t show it that much,” Sevastova said.
“I don’t play drop shots when I see the player struggling, I just play them instinctively; sometimes they don’t work.”