Great Britain's Joanna Rowsell claimed her second gold of the World Track Championships with victory in the individual pursuit in Cali, Colombia.
The 25-year-old beat five-time champion Sarah Hammer of the United States by 1.2 seconds in a personal-best time of three minutes 30.318 seconds over 3km.
Rowsell, who won gold in the team pursuit 24 hours earlier, said: "I can't believe I went that quick.
"This has been a goal for a while. It means the world to me."
Rowsell led Hammer, the 30-year-old defending champion, by a second after the first lap, and never relinquished her advantage as she claimed a first individual world title after four gold medals in the team event.
Australia's Amy Cure took bronze in 3:36.174.
Rowsell added: "I was ill with a chest infection two weeks ago so I missed three team training sessions, which in hindsight perhaps did me good - gave me a bit more rest. I wasn't bed-bound, but I couldn't train."
Meanwhile, her fellow Briton Jess Varnish reached the semi-finals of the women's individual sprint with victory over defending champion and team-mate Becky James.
Varnish, who won bronze with James in the team sprint on the opening day of the Championships, triumphed 2-0 despite a fall which prompted a restart in the second race.
She faces China's Tianshi Zhong for a place in Saturday's final, against defending champion Kristina Vogel of Germany or China's Junhong Lin.
James shared a hug with her team-mate afterwards but was angry at herself for her tactical selection.
The 22-year-old from Abergavenny, who responded by winning the race for fifth, said: "I've no idea why we decided to go for those tactics.
"It's upsetting because I wanted to defend my world title, especially after qualifying second. My legs felt great today."
She added that there were no hard feelings with Varnish.
"We're really good friends off the track and worst enemies on the track. That's how sport is," added James.
"We've both been practising track standing and slow riding together in Manchester.
"When I felt her hit my back wheel and I just saw her tumble we both had a bit of a giggle."
In the men's 1km time trial, Britain's Kian Emadi finished 12th in 1:02.220 - he was fourth last year - as Frenchman Francois Pervis successfully defended his title in a Championship-record time of 59.385 seconds.
Briton Ed Clancy lies sixth overall after three of the six events in the men's omnium. Although he won the first event, the flying lap, he could manage only 13th in the points race and eighth in the elimination race. France's Thomas Boudat led the competition overnight.
Colombian Edwin Avila took gold in a thrilling 40km men's points race in front of his home crowd.