The reigning women’s champion, Sloane Stephens, succumbed to the tenacity of Anastasija Sevastova as well as the stifling heat and humidity that enveloped the Arthur Ashe Court as the upsets kept coming on day nine of the US Open. Roger Federer complained about the humidity during his shock defeat by the Australian underdog John Millman in the early hours of the morning but there was the added dimension of burning heat in still, unforgiving air when Stephens and Sevastova stepped on to the same court at noon. The Latvian, ranked No 18 in the world, fully deserved her 6-2, 6-3 win, although Stephens fought all the way to the end when visibly suffering. Where Stephens has used tennis to lift herself from adversity, Sevastova, introduced to the game by her grandmother, did not play competitively until she was 15, quit the sport in 2013, disillusioned with the grind of the Tour, and moved to Vienna, where she still lives, to study leisure management. There was nothing leisurely about her performance on Tuesday, and she mixed delightful drop shots and chips with some rasping groundstrokes to torment the suffering champion. This was Sevastova’s third quarter-final here in a row and she is in the semi-finals of a major for the first time. “It was very physical, so hot,” she said courtside. “The first set was crucial. I showed some nerves in the end but it’s normal. I stuck to my game plan, to move well and take my chances.” Stephens dropped serve to go 3-1 down in the second set and, when Sevastova drop-shotted the American to go 40-love up on her serve, Stephens barely bothered to respond. The heat was so intense, a boys match on Grandstand was suspended after only 36 minutes and 10 other junior matches were stopped. Back on Ashe, they had been playing for just over an hour. Then, on the point of collapse Stephens won eight points in a row to get back on serve. It was a monumental effort. A run of 11 consecutive points came to an end, though, when she netted a routine backhand volley. Stephens saved break point and fought through four deuce points but could not reach another drop shot from Sevastova, who served out with new balls from the shaded end. It hardly seemed fair. Stephens saved two match points but dumped a tired backhand and it was done. It takes a lot for a visiting player to win over an American audience playing one of their own but Juan Martín del Potro, who won here as a prodigy in 2009, was that man again on Tuesday when he beat John Isner 6-7 (5), 6-3, 7-6 (4), 6-2 in what he described as “impossible” conditions in the quarter-final. “I’m so happy to reach another semi-final in my favourite tournament, which is very special to me,” the Argentinian said, drenched from his effort, to loud acclaim on court. “Of course beating John in this sort of match is epic. We both fought all the match. I survived with my serve at a couple of points.” He dragged his 6ft 6in frame to the locker room in the mandated heat break after three sets and described how it got him through the final set. “I took a shower and re-taped my ankles, lay down on the table – and I did not want to come back. It’s impossible to play tennis in this heat but this crowd are great.” Among the fans were a group of friends Del Potro had brought from Argentina. “If I meet them [before the semi-finals on Friday], it is dangerous for me. I will stay resting in my hotel, then afterwards we will have a chance to have fun together. They are so good.” If anyone was biologically suited to move with maximum efficiency in the New York heat that has plagued most days of this tournament it surely would be del Potro and 6ft 10in Isner. They move like glaciers between points but find the after-burners when they need them. Up two sets and 5-2 after nearly three-and-a-half hours, del Potro received a one-minute massage on his thighs during the last changeover for what looked like fatigue or cramping. Isner also had been close to seizing up more than once in the killing conditions. Del Potro drove Isner to deuce twice on his last serve, fashioned match point with a belting forehand and was relieved to see his exhausted opponent put a concluding, wary forehand into the net.<doc-sep>Sloane Stephens will not defend her 2017 U.S. Open title, as she was defeated in the quarterfinals by 19-seed Anastasija Sevastova. (Photo by Al Bello/Getty Images) Sloane Stephens’ defense of her 2017 U.S. Open title ended on Tuesday in the quarterfinals. Anastasija Sevastova, the 19-seed from Latvia, stunned Stephens with 6-2, 6-3 victories in straight sets. Sevastova will be advancing to her very first Grand Slam semifinal. Sevastova looked rocky in the first set, but took advantage of uncharacteristically slow play from Stephens and won the first set 6-2. Stephens was on the ropes early in the second set with a deficit of 2-0, but started to make a comeback. After she won her first game of the second set, she let out a triumphant, Serena Williams-esque roar. It looked like things might be turning around. But then Stephens dropped the next game, and the the next one. She was finally able to answer back with a win in the sixth game to bring her to 4-2, though that also came with a language warning from the umpire. She got closer to Sevastova with a win in the seventh game, looking more like the Sloane Stephens everyone expected to see. She tried to take that momentum into game eight, but missed several opportunities to tie Sevastova — including a heartbreaker after a 14-shot volley that saw Stephens hit it into the net. The advantage went back and forth, with Sevastova finally winning and going up 5-3. Sevastova sealed the upset a game later. Overall, Stephens looked tired and low-energy. The Open announcers said that she was battling a cold, and the absolutely stifling conditions weren’t helping her energy level. Her footwork wasn’t quite as sharp as normal, and she had told the announcers at one point that she wasn’t playing at 100%. It showed on the court, with her giving up on drop shots and bending over to lean on her thighs during brief breaks between serves. That both players didn’t completely collapse from the extreme heat is a triumph in itself — play at the junior level was suspended due to the conditions, but the adult circuit has a higher heat threshold to suspend play. Stephens played the second set with the sun pounding down on her, and the announcers said that only three games all tournament had been won in the sun. Story continues Sevastova, who has retired and made a comeback in her career, has been to the quarterfinals of a Grand Slam three times, but never to the semifinals. Now that she’s avenged her loss to Stephens last month in Montreal, she will face the winner of the match between Serena Williams and Karolína Plíšková, which will be played Tuesday night. – – – – – – Liz Roscher is a writer for Yahoo Sports. Have a tip? Email her at lizroscher@yahoo.com or follow her on Twitter at @lizroscher. More from Yahoo Sports: • Angry Nike customers are setting their gear on fire • Charles Robinson: ‘The most controversial move that Nike has ever made’ • Pete Thamel: Taggart’s FSU debut goes down in flames • ESPN announcer taken off Washington games<doc-sep>Defending champion Sloane Stephens was eliminated from the US Open on Tuesday, beaten by Anastasija Sevastova 6-2, 6-3 in the quarter-finals. Stephens beat Sevastova in the same round last year en route to her first Grand Slam title, but she missed numerous chances to grab an early lead in the rematch and could never get back into the match. Sevastova, the No 19 seed from Latvia, will play either Serena Williams or 2016 US Open runner-up Karolina Pliskova in her first Grand Slam semi-final. Anastasija Sevastova celebrates after beating Sloane Stephens in the US Open last eight Defending champion Stephens seemed to struggle in the sweltering heat in New York Three-quarters of Arthur Ashe Stadium was in the sun on another day of more than 90-degree temperatures in New York. Stephens seemed to lack some of her usual sideline-to-sideline court coverage in the heat. But her serve was the bigger problem. The No 3 seed was broken five times in the 84-minute match.<doc-sep>
Sloane Stephens' US Open defence ended by Anastasija Sevastova Sloane Stephens' US Open title defence ended in a stunning straight-sets defeat by Latvia's Anastasija Sevastova on Tuesday. Stephens, who was aiming to become the first woman to successfully defend a Grand Slam title since Serena Williams triumphed at Wimbledon in 2015 and 2016, started the day's action on Arthur Ashe Stadium against 19th-seeded Sevastova. The 25-year-old American, who struggled after her triumph last year, came in as the heavy favourite to defeat her opponent in a rematch of her three-set victory in the same round at Flushing Meadows last year. But Sevastova defied the odds to become the first Latvian woman to reach the semi-finals of a Grand Slam for the first time with an impressive 6-2 6-3 victory. Sevastova recorded the biggest win of her career as she reached the semi-finals of the US Open She will face either 23-time major champion Serena Williams or eighth-seeded Czech Karolina Pliskova for a place in the final. In stiflingly hot conditions, Sevastova broke Stephens twice in the opening set before breaking again to go up 2-0 in the second set before Stephens, who was visibly wilting on the sun-baked court, broke back to tie things up 2-2. But Sevastova broke again, then stumbled over the line after Stephens netted her return on her third match point. "I think it was very physical today. It's tough to play, so hot in here. The first set was so important," said Sevastova. "When the shade was there it was so hot here and amazing there. The last games, it was good that I played in the shade. The sun was not comfortable and it was hot." Stephens joined an exodus of women's seeds that saw top-ranked Simona Halep and No 2 Caroline Wozniacki exit in the first two rounds. Early in her career, Sevastova retired from tennis due to injuries and disillusionment from the sport. She now finds herself in the semifinal of a Grand Slam and this is what it means...#USOpen pic.twitter.com/Ws2ya4mivQ — US Open Tennis (@usopen) September 4, 2018 We have every major tennis event covered from all angles via our website skysports.com/tennis. On the move? Head to our app for mobile devices and iPad, or follow our Twitter account @SkySportsTennis to join in the conversation. Tennis is back on Sky Sports screens with the Laver Cup in September while we will also have coverage of the ATP Finals in November with every match live on Sky Sports. But first, we will be across the final major of the year in New York as the US Open right through to the final with live blogs, reports, features and reaction.