Katie Boulter Loses 6-1, 6-0 to Karolina Muchova in Worst Grand Slam Defeat of Her Career

Katie Boulter's US Open ended Wednesday in a 6-1, 6-0 defeat to Karolina Muchova in 58 minutes.

The British No. 1 lost seven service games out of seven. She hit eight double faults and zero aces. She won just 33% of points on her first serve, per BBC Sport. Four winners against 21 unforced errors, according to The Independent, or 22 by BBC Sport and Yahoo Sports' count.

Muchova, the seventh seed and this year's Wimbledon runner-up, needed 14 winners and committed only nine unforced errors, according to BBC Sport. The Czech player mixed drop shots with deep, flat groundstrokes and never let Boulter settle.

The match wasn't supposed to happen where it did. It was originally slotted for an outer court, but heavy rain hitting the Billie Jean King National Tennis Center forced organizers to move it under the retractable roof at the 14,000-seat Louis Armstrong Stadium, according to BBC Sport and The Guardian. Boulter had played there exactly once before, in practice.

Boulter actually started fine. She broke Muchova's opening service game and forced another break point in the second, according to The Independent and The Gazette. Then it fell apart completely. She didn't win another game the rest of the match.

Boulter, 30, pointed to the atmosphere afterward. "I struggled with the conditions. I struggled with the roof, the noise, I let things distract me," she said, according to BBC Sport. "I'm not usually aware of everything going on. It made me feel a little bit uncomfortable. I have to deal with it better."

She expanded on it to The Guardian, saying she expected the crowd noise to die down once the match started, the way it usually does. "It never changed," she said. "So I think in my mind I was like, 'Okay, so you need to adjust here.'" She called it "a very different feeling" and "a little abnormal for me."

Former world No. 5 Daniela Hantuchova offered sharp criticism on BBC Radio 5 Live. "I would be really humbled, I would sit down with my team and say 'OK, we need to change something big time,'" Hantuchova said. "It was very obvious today that it was the serve. I feel like it needs to be cleared up because she was losing the rhythm and not using her legs." Hantuchova said if she were Boulter, she'd be on the practice court the next day.

The loss capped a rough season at the majors for Boulter, who came into the tournament ranked world No. 62. She's now won just two matches across four Grand Slam tournaments this year, and only two of her last six matches overall since a first-round exit at Wimbledon, according to BBC Sport. That stretch includes a five-match losing run that only broke with a first-round win in Cincinnati last month.

It hasn't all been bad. Boulter won her fourth WTA title in Ostrava this year and beat world No. 2 Elena Rybakina at Queen's Club, according to The Guardian. And her personal life has been a highlight: she married Australian world No. 7 Alex de Minaur in July.

Other British players had a mixed day at Flushing Meadows. Jacob Fearnley lost to Argentina's Tomas Martin Etcheverry 6-3, 6-3, 3-6, 6-3, according to Occasional Digest. Toby Samuel fell to Czech player Jiri Lehecka. Jan Choinski was beaten in straight sets, 6-3, 6-1, 7-6 (5), by Dutchman Botic van de Zandschulp, according to The Independent. Francesca Jones was the bright spot, finishing off a rain-interrupted first-round win over Poland's Magda Linette to reach the second round.

Muchova moves on to the third round. What's unresolved is what Boulter and her team do next. Hantuchova's diagnosis was specific: fix the serve mechanics, get back on the practice court immediately. Whether Boulter's team makes that change, or writes this off as an isolated bad night under an unfamiliar roof, will show up in her results at her next tournament.