US Open Highlights 7th day: Sharapova ousted while Venus, Kvitova advance

Czech Petra Kvitova added another chapter to her comeback story by stunning Wimbledon champion Garbine Muguruza in straight sets to reach the U.S. Open quarter-finals, while Maria Sharapova's return to the big stage ended in defeat to Latvian Anastasija Sevastova. Kvitova, whose progress has been slow but steady since a horrifying knife attack on her left hand in December, showed similar fighting spirit that won her the Birmingham title this year as she dismissed the third seed 7-6(3) 6-3 in one hour and 45 minutes. The twice Wimbledon champion, playing in only her eighth tournament since her career-threatening injury, set up a last eight clash with Venus Williams after the American dumped out Spaniard Carla Suarez Navarro 6-3 3-6 6-1. Venus has reached grand slam finals at the Australian Open and Wimbledon this year and Kvitova said she would have a tough task ahead.

"I just like to play on the big stages against the great players on the tour, so... I like those challenges." @Petra_Kvitova #USOpen pic.twitter.com/5TEvZoYBut

— US Open Tennis (@usopen) September 4, 2017

"It will be a great match for me to step on Ashe again probably and play there. I mean, we always had tough battles. I will try my best. I mean, she has a big serve, big server of course," she said. Wildcard Sharapova, who played in her first major since a 15-month doping ban, said there were a lot of positives in her defeat by Sevastova. "Just competing, you know, being in that competitive environment. That's what I missed," she said. Sharapova's power play was nullified by the 16th seed's control and delicate touch, and she eventually ground out a 5-7 6-4 6-2 win in two hours and 16 minutes. Sevastova meets the unseeded Sloane Stephens after the American reached the quarter-finals for the first time in her career with a 6-3 3-6 6-1 win over Julia Goerges of Germany. Sam Querrey, the last American standing in the men's singles, powered past Germany's Mischa Zverev 6-2 6-2 6-1 in one hour and 15 minutes, the shortest completed men's singles match of the tournament so far. Next up for Querrey, the first American man to reach the U.S. Open quarter-finals since 2011, is South Africa's 28th seed Kevin Anderson, who outlasted Italian Paolo Lorenzi 6-4 6-4 6-7(4) 6-4. Canadian teenager Denis Shapovalov was knocked out by Pablo Carreno Busta 7-6(2) 7-6(4) 7-6(3) and the Spaniard was joined in the last eight by Argentine Diego Schwartzman who downed 16th seed Lucas Pouille of France 7-6(3) 7-5 2-6 6-2. Highlights from day seven of the U.S. Open tennis championships on Sunday (times GMT): QUERREY KNOCKS OUT ZVEREV - Sam Querrey, the last American standing in the men's singles, blasted 55 winners and 18 aces in his routine 6-2 6-2 6-1 win over Germany's Mischa Zverev in one hour and 15 minutes. - Querrey, seeded 17th, meets South Africa's Kevin Anderson in the quarter-finals. KVITOVA STUNS MUGURUZA, ENTERS LAST EIGHT - A resurgent Petra Kvitova stunned Spain's Wimbledon champion and third seed Garbine Muguruza 7-6(3) 6-3 to enter the quarter-finals in one hour and 45 minutes. - The 13th seeded Czech, a two-time grand slam champion, faces American Venus Williams next. ANDERSON MARCHES INTO QUARTER-FINALS

.@Petra_Kvitova will play Venus Williams after defeating Muguruza tonight on Ashe. #USOpen @MBUSA pic.twitter.com/r7oTDoZ72S— US Open Tennis (@usopen) September 4, 2017

- South Africa's Kevin Anderson, the men's 28th seed, beat Italian Paolo Lorenzi 6-4 6-4 6-7(4) 6-4. - Anderson faces either Germany's Mischa Zverev or American Sam Querrey in the quarter-finals. VENUS KEEPS HOME SLAM HOPES ALIVE - Venus Williams advances to the quarter-finals with a 6-3 3-6 6-1 win over Spaniard Carla Suarez Navarro.

POINT of the MATCH: This one had us on the edge of our seats...@Venuseswilliams ? @CarlaSuarezNava#USOpen pic.twitter.com/CJKevZEAz6

— US Open Tennis (@usopen) September 3, 2017

- The ninth seed will play either Czech Petra Kvitova or reigning Wimbledon champion Garbine Muguruza next. SCHWARTZMAN ENDS POUILLE'S RUN AT U.S. OPEN - Argentine Diego Schwartzman knocked out men's 16th seed Lucas Pouille of France 7-6(3) 7-5 2-6 6-2 to reach the last eight. - The unseeded Schwartzman, who beat fifth seed Marin Cilic in the third round, meets 12th seeded Spaniard Pablo Carreno Busta for a place in the semi-finals. SHARAPOVA KNOCKED OUT BY SEVASTOVA - Russian wild card Maria Sharapova was knocked out of the U.S. Open in the fourth round after losing 5-7 6-4 6-2 to Latvian 16th seed Anastasija Sevastova.

.@MariaSharapova on her US Open return. "Reflecting back on the week, I can be happy." https://t.co/BkelWHZgVj #usopen pic.twitter.com/gMdOwgoNcR— US Open Tennis (@usopen) September 3, 2017

- Former world number one Sharapova made a total of 51 unforced errors as she crashed out. - Sevastova faces American Sloane Stephens in the quarter-finals. STEPHENS THROUGH AFTER DOWNING GOERGES - Unseeded American Sloane Stephens reached the quarter-finals for the first time after beating women's 30th seed Julia Goerges of Germany 6-3 3-6 6-1.

Congrats to @SloaneStephens as she heads into the QFs! ? #USOpen @MBUSA pic.twitter.com/WilkiMzYI7

— US Open Tennis (@usopen) September 3, 2017

CARRENO BUSTA BEATS SHAPOVALOV - Spain's Pablo Carreno Busta won a hard-fought match against Canada's Denis Shapovalov, beating the 18-year-old 7-6(2) 7-6(4) 7-6(3) to reach the quarter-finals. - The 12th seed has reached the last eight of the U.S. Open for the first time and will face either Argentine Diego Schwartzman or Frenchman Lucas Pouille. - Carreno Busta also reached the quarter-finals of the French Open this year.