Instead, the 24-year-old qualifier battled through oppressive heat and humidity for three hours and 23 minutes in a historic 7-6 (7/4), 6-7 (4/7), 6-2 triumph over Wimbledon runner-up Garbine Muguruza, the ninth seed from Spain.
"It's a horrible situation to be in," Konta said. "It was definitely hot out there. I'm already a sweater so I was really perspiring. I dealt with it the best I could. I was hydrating. I was nibbling on a banana."
The marathon match lasted seven minutes longer than the old mark set in 2011 when Samantha Stosur defeated Nadia Petrova on her way to the title.
"I noticed after the first set it was incredibly long, but then after I had a couple glances on the clock, I'm like, 'OK, we have been here for a while,'" Konta said.
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"But it's difficult with sweating buckets. After changing the clothes, they literally weighed like a lot. I'm just happy I was able to put that to the back of my mind, because it's completely out of my control.
World number 97 Konta battled through for her 15th victory in a row, although most of them came in events below the WTA Tour level. She faces German 18th seed Andrea Petkovic next.
"Every opponent is a new opponent. Trust me, they don't give a crap how many matches I have won," Konta said.
Konta is enjoying the moment while Serena Williams, on the opposite side of the draw, goes for a calendar Slam, an Open Era-record matching 22nd career Slam title and her fourth US Open title in a row.
"I am going to lose sooner or later. I'm not invincible. I'm no Serena Williams," Konta said. "I'm just honestly happy to be still in this tournament and get another opportunity to compete. I'm very humbled about this experience."
"It's breaking little records," she said. "I lost that. It's nice to win one.