Rebecca Cooke confirmed her billing as a medal prospect at the World Swimming Championships by qualifying fastest for Tuesday's 1500m freestyle final.
The Glaswegian's time of 16 minutes 15.69 seconds in Montreal was more than two seconds faster than American Laura Conway who was second in 16:17.97.
City of Newcastle's Chris Cook also gave Britain a lift when he came sixth in the 100m breastroke final in 1:0.99.
GB's Liam Tancock also qualified for Tuesday's 100m backstroke semi-final.
Tancock's time of 55.47 was good enough to see him go through as 14th fastest, but fellow Briton James Goddard missed out when he finished 17th in 55.66.
Meanwhile, Cook immediately set his sights on qualifying for the 2006 Commonwealth Games at next month's trials.
"I tried a few different things out there but this was all about getting more experience," he admitted.
"I was pleased to make the final and I enjoyed myself. Obviously I am looking ahead to the Commonwealth Games, but I need to get through the trials first."
But Kirsty Balfour missed the cut in the women's 100m breastroke when she touched home 21st in 1:10.32.
Loughborough-based teenager Kate Haywood also failed to go through in the same event, missing out on qualification by just over a tenth of a second.
Haywood finished fifth in her semi-final in 1:08.65 - nearly half a second slower than the British record she set early this year.
Haywood's time was the 10th fastest with only the top eight advancing to the final.
She said: "I am a little bit disappointed and I was hoping to go quicker, it just did not happen for me. The last 25m I thought I was slipping through the water."
Haywood's Loughborough team-mate David Carry finished 12th fastest in themen's 200m freestyle semi-finals in 1:48.79, well down on the personal best he set during the world trials.
"It was a very competitive race but I would have liked to have finished further up the field," said Carry.
"I am just a bit off my best but this is my first major international championships and I am still learning."
Meanwhile, Gemma Spofforth's time of 1:04.88 in the women's 100m backstroke heats left her down in 33rd place.