Sloane Stephens reacts in a women's singles quarterfinal match against...

Sloane Stephens reacts in a women's singles quarterfinal match against Anastasija Sevastova during the U.S. Open at the USTA Billie Jean King National Tennis Center on Tuesday, Sept. 4, 2018. Credit: Getty Images/Al Bello

The tank ran empty for Sloane Stephens on Tuesday.

The defending champion of the U.S. Open withered under the constant, penetrating, oppressive heat in Arthur Ashe Stadium and lost to Anastasija Sevastova, 6-2, 6-3, in the first of the women’s quarterfinals.

Stephens had beaten Sevastova in last year’s quarters, digging out a three-set victory after being down 3-1 in the third. There would be no escape act this time. A combination of Stephens’ ineffectual play and Sevastova’s cunning was enough to put the Latvian into the semifinals of a Grand Slam for the first time.

After a lackluster first-set effort (and a number of Sevastova’s winning slice backhand drop shots) Stephens was broken in the second game of the second set, then earned a break back in the next game. But she couldn’t hold it. After being broken in the fourth game, Stephens sunk to her knees. It was pretty much over then.

“I think today I just really couldn't get anything to connect,” Stephens said. “Even when I did have my break opportunities, I just wasn't playing the points well at all. Mentally, physically, I just wasn't connecting. It just was a really tough day. The heat doesn't make it any more fun.”

She was also suffering from a sinus infection, though she didn't use that as an excuse.

“Nothing was wrong with me before the match,” Stephens said. “I was excited to play, happy to get out there and compete. Like I said, today was a bad day. I wish I could have played better. The better player won.”

It was Sevastova’s third straight quarterfinal at the U.S. Open.

“I think it was third time lucky,” she said. “But again, if I would lose I would also be proud of myself. Three times quarters. It's not happening every year or every day.”

As for the challenging conditions, Sevastova said: “It’s always tough in the beginning, I think, but then you get in the flow and you just forget it.

I think shade was also pretty tough. It's moving, and, yeah, one side with the sun was very hot. Very hot.”

Stephens leaves Flushing Meadows feeling as if she did the best she could and looking forward to the Asia swing in the fall where her play dropped precipitously last year.

It’s been a pretty good season with a win in Miami and losses to Simona Halep in the finals of the French Open and Montreal tournaments.

“So the fact that I made it to the quarterfinals and played some really good matches and I just competed as hard as I could, I mean, a lot to be proud of,” Stephens said. “And obviously defending a title is very hard, very difficult. If you were defending, you'd be playing the same exact people all over again, which I didn't. I made the most of it this week or the last, whatever, 10 days, whatever it was. I can be proud of a lot of things that happened the last couple, the matches that I played, so I'm not going to dwell on it.”

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