Annoyed by her 500-metre performance earlier in the day, Nesbitt set a cracking pace from the start gun in the 1,000 and put down a time of one minute 12.68 seconds at the Olympic Oval in Calgary.
The 26-year-old from London, Ont., bettered the previous world record of 1:13.11 set by Canada's Cindy Klassen in 2006 on the same ice.
"It felt really, really powerful and the first time this year it felt like every single stride, I felt a lot of pressure and power going into the ice," Nesbitt said.
Nesbitt is the Olympic champion in the 1,000 metres, winning gold at the 2010 Winter Games in Vancouver.
"This was a better race than my Olympic gold-medal race, so that's really cool," she said. "I think it's probably one of biggest accomplishments to set a world record and on top of that, one of Cindy's."
Nesbitt is the defending world women's sprint champion. She led after the first day of competition Saturday and will race another 500 and 1,000 on Sunday when the men's and women's winners are crowned.
The sprint title is determined by skaters' times over two distances — the 500 and the 1,000 — skated twice. times are converted into points. Nesbitt ranked ahead of Jenny Wolf of Germany by .56. Hong Zhang of China was third, .58 behind Nesbitt.
A slight slip coming out of the first turn in the 500 earlier Saturday had Nesbitt flailing her arms momentarily. The mistake cost her time as she finished eighth.
"I was pretty frustrated after my 500," she admitted. "I thought I had a good race even though I had a slip in the first corner. Then I saw the finishing time and was not happy with it. It felt better than the time reflected."
"I was kind of going through all different scenarios in my head before the 1,000. I kind of got a little bit angry and I race well when I'm angry, so I think it was good."
Nesbitt was advantageously paired in the 1,000 with Annette Gerritsen of the Netherlands, a notoriously fast starter whom Nesbitt used as her pacer.
"I wanted to keep her as close as I could and kind of pull her in as quickly as possible," Nesbitt explained. "I was actually able to do that in the first 200 metres, which was unusual for me."
Nesbitt kept pushing the pace because she thought Gerritsen might be having an off-day. She could hear her world-record split times called over the loudspeaker. That was concerning to her because Nesbitt thought she might not be totally focused on her race.
"I think I'm one of the best technical skaters in the world and that's what I strive to be," Nesbitt said. "Even when I have a day where physically I don't feel good, technically I can make up for it. I think I just executed the race quite well."
Nesbitt said her 1,000 didn't feel like a perfect race. Her coach Xiuli Wang, who has also coached Olympic champion Clara Hughes and multi-medallist Kristina Groves, said Nesbitt's high standards are what make her so formidable in the sport.
"If she says 'this is not perfect' the race, it means deep in her heart and in her head, she can do better," Wang said. "I want my athletes do to that, instead of everything in the comfort zone.
"For her race today, she did a great opener . . . she did great on her entrance (into the corners) and her race after the opener, the two laps were really smooth. Beautiful skating, but before the 1,000 metres she was pretty pissed off. Sorry I used that word."
The Olympic Oval in Calgary and the Oval in Salt Lake City from the 2002 Winter Olympics are considered the fastest ovals in the world as virtually every current record was set on one or the other. The women's 1,000 was the only world record to fall Saturday, although Nesbitt gets a chance to skate it again Sunday.
Kyou-Hyuk Lee of South Korea led the men's field ahead of runner-up Dmitry Lobkov of Russia and Stefan Groothuis of the Netherlands.
Muncef Ouardi of Quebec City was the top Canadian male in eighth overall, with Jamie Gregg of Edmonton in 10th and Denny Morrison of Fort St. John, B.C., in 11th.
Winnipeg's Shannon Rempel ranked 20th and Kaylin Irvine of Calgary 24th among women. Rempel was a last-minute replacement for Calgary's Anastasia Bucsis, who withdrew because of a sore back.
Klassen set the previous women's 1,000 record just a few weeks after her historic five-medal performance at the 2006 Winter Games in Turin, Italy. She still holds the world's fastest times in the women's 1,500 and 3,000 metres. Klassen is still racing World Cup events for Canada, but is not competing at the sprint championship this weekend.