Weary Boutier still alive in LPGA Match Play after 45-hole day
The 31-year-old 11th seed's exhausting day began in the last 16, when her match against South Africa's Ashleigh Buhai finished all-square after 18 holes at the Shadow Creek Golf Course in Las Vegas.
That sent both players into a marathon session of dramatic sudden death, which Boutier won on the 28th hole -- the longest match in tournament history.
"It was definitely tough, definitely a grind," Boutier said.
"I feel like we both played pretty steady and went back and forth a lot. I had a few chances, and she had a few chances, so it was just all the way until the end, but I'm glad it's over."
After that energy-sapping victory, Boutier had just 30 minutes before she was back out on the course for her quarter-final against Sagstrom.
Another tense tussle unfolded, with the players level after 17 holes when darkness halted play.
Boutier and Sagstrom will return early on Sunday to play the 18th, with a possibility of even more playoff holes.
"It was a very long day," Boutier said after play was suspended.
"I feel kind of tired, but I feel like it was a good match again this afternoon, very tight and going back and forth with Madelene. So just got to keep pushing tomorrow."
Boutier or Sagstrom will face a semi-final against Angel Yin of the United States, who beat Thailand's Jeeno Thitikul 4&2.
Fellow Thai Ariya Jutanugarn reached the semi-finals by defeating Sweden's Maja Stark 4&2
Ariya will face Lauren Coughlin of the United States after Coughlin had a one-up win over Australia's Stephanie Kyriacou.