NEW YORK — Wilting in high heat and humidity Monday, Eugenie Bouchard became the latest top woman to lose at the US Open, ending her streak of making the semifinals at each Grand Slam tournament this year.
The seventh-seeded Bouchard, the runner-up at Wimbledon in July, needed a medical timeout and was beaten, 7-6 (7-2), 6-4, by 17th-seeded Ekaterina Makarova.
In muggy air with temperature in the high 80s, a trainer checked Bouchard’s blood pressure and rubbed plastic bags of ice on her shoulders, arms, and legs during the changeover after the second set’s fifth game.
When action resumed, the 20-year-old Canadian got broken right away to trail, 4-2. She broke Makarova and pulled even, but was broken at love in the final game to end it.
‘‘I definitely felt a lot of outside expectations and pressure to win matches. I felt more like it’s normal if I win and it’s a bit more of a disaster when I lose,’’ Bouchard said. ‘‘But that’s something that I need to block out.’’
Asked what went through her mind during Bouchard’s medical break, Makarova smiled.
‘‘Well, actually, I thought, ‘Thanks,’ because I also was tired,’’ Makarova said with a smile. ‘‘It was really [helpful] for me also.’’
Bouchard’s loss means that for the first time since 1977, eight different women will have filled the eight finalist slots at a season’s Grand Slam tournaments:
■ Li Na beat Dominika Cibulkova at the Australian Open in January; Li didn’t even enter the US Open because of a knee injury, while Cibulkova was stunned by 15-year-old American CiCi Bellis in the first round.
■ Maria Sharapova edged Simona Halep at the French Open in June; Sharapova lost to Caroline Wozniacki in the fourth round in New York, and Halep went out in the third round against qualifier Mirjana Lucic-Baroni.
■ Petra Kvitova defeated Bouchard at Wimbledon in July; Kvitova departed in the third round in Flushing Meadows against 145th-ranked qualifier Aleksandra Krunic. Her surprising run was ended by two-time US Open runner-up Victoria Azarenka.
The 16th-seeded Azarenka won four of the last five games to edge Krunic, 4-6, 6-4, 6-4.
Krunic was trying to become the first qualifier since 1981 to reach the quarterfinals at Flushing Meadows.
While Makarova is into the US Open quarterfinals for the second year in a row, Bouchard’s early-for-her major exit certainly fits with the way things have gone the past eight days. Of the top 10 seeded women, only two remain: No. 1 Serena Williams and No. 10 Wozniacki.
Williams got to her first Grand Slam quarterfinal of 2014 by overwhelming 50th-ranked Kaia Kanepi, 6-3, 6-3, winning her first 12 service points with the help of five aces.
Through four matches, Williams, 32, has lost only 17 games — the eighth time she’s made it to the US Open quarterfinals dropping that many or fewer.
One of the few glitches for Williams came when she tried to serve for the match at 5-2 in the second set.
She double-faulted twice to hand over a break to Kanepi, who promptly converted it with a backhand winner down the line.
After breaking back to win, Williams acknowledged feeling a bit of pressure to make up for her showings at the year’s other majors — fourth round at the Australian Open, second round at the French Open, and third round at Wimbledon.
‘‘I think I felt it in my service game,’’ Williams said. ‘‘I'm like, ‘Can I please make it to a Grand Slam quarters this year?’ ’’
Next for Williams in her pursuit of a third straight US Open title and 18th Grand Slam championship is 11th-seeded Flavia Pennetta, who beat 29th-seeded Casey Dellacqua, 7-5, 6-2.
Pennetta, a semifinalist a year ago, has lost all five previous meetings against Williams.
‘‘You cannot invent something. I mean, you just have to play your tennis,’’ Pennetta said. ‘‘Of course, she’s better than me, but if I still believe I can beat her, maybe if she doesn’t have a good day, I can do that.’’
The top-seeded man, Novak Djokovic, played mostly mistake-free tennis, making only 19 unforced errors and facing only two break points — both saved — in a 6-1, 7-5, 6-4 victory over 22d-seeded Philipp Kohlschreiber.
In a fourth-round men’s match Monday night, No. 3 Stan Wawrinka brushed off a tumble into the stands and beat No. 16 Tommy Robredo 7-5, 4-6, 7-6 (9-7), 6-2.
Djokovic, the 2011 US Open champion, earned a spot in the quarterfinals for the eighth year in a row — and at a 22d consecutive Grand Slam tournament overall.
The last time Djokovic was eliminated before the quarterfinals at a major was a third-round loss to Kohlschreiber at the 2009 French Open.
Djokovic now meets No. 8 Andy Murray, who got past No. 9 Jo-Wilfried Tsonga, 7-5, 7-5, 6-4, in 2 hours, 35 minutes