Britain's James Gibson suffered a huge disappointment at the World Swimming Championships on Tuesday when he failed to make the men's 50m breastroke final.
Gibson could only finish 12th fastest in the semi-finals
Gibson had vowed to defend the title he captured in Barcelona two years ago but his semi-final time of 28.18 seconds was not good enough to see him through.
But Chris Cook ensured Britain will be represented in Wednesday's final when he qualified fifth fastest overall.
Cook smashed his personal best to touch home in 27.91 secs in Montreal.
Afterwards, Gibson branded himself "an idiot" for getting off to a poor start.
"I got washed away a bit and left behind. It is perfect conditions and a great arena to swim in, I can't blame anyone but myself," he said.
Cook, meanwhile, admitted he was surprised to advance after being drawn in lane one for his semi-final.
"I'm surprised, but delighted. I didn't feel great in the heats," he said.
"But if you have got a lane, you have got a lane - any lane is good to win. You have just got to go for it and I am delighted with that time."
Britain's Rebecca Cooke also suffered heartache when she missed out on a medal in the women's 1500m freestyle final.
The Glasgow swimmer had led qualifying and held third spot early in the final but her challenge quickly faded and she trailed home in seventh.
Cooke's time of 16 minutes 23.25 seconds was nearly 10 seconds off her British record and nine seconds adrift of the mark she set in Monday's heats.
America's Kate Ziegler won in 16:00.41 ahead of Swiss Flavia Rigamonti, who finished second in 16:04.34.
Brittany Reimer of Canada was third in 16:07.73.
Cooke now aims to learn from the bitter experience ahead of Friday's 800m freestyle.
"I have to assess how I swim in the heats and conserve my energy better for finals," she said.
"I rarely swim back-to-back 1500m at international level, so two races in two days is quite a lot.
"Perhaps it is taking more out of me than I thought. Hopefully I can come back in the 800m."
Meanwhile, Michael Phelps claimed his second gold medal of the championships when he won the men's 200m freestyle.
Phelps, who helped the USA to the 4x100m freestyle title on Sunday, clocked 1:45.20 to edge rival Grant Hackett.
Australian Hackett finished second in 1:46.14 to add a silver medal to the gold he won in Sunday's 400m freestyle.
South Africa's Ryk Neethling came home third in 1:46.63.
Phelps' US team-mate Aaron Peirsol won the men's 100m backstroke final.
Peirsol led all the way to take the gold in 53.62 - well outside of the world record of 53.17 he set in April.
Fellow American Randall Bal finished second in 54.02 and Hungary's Laszio Cseh placed third in 54.27.
Zimbabwe's Kirsty Coventry won the women's 100m backstroke gold as world record holder Natalie Coughlin was relegated to third.
Coventry touched home in 1:00.24 ahead of Germany's Antje Buschschulte, who recorded 1:00.84.
American Coughlin clocked 1:00.88.
Australia's Leisel Jones won the women's 100m breaststroke final.
Jones stormed home in the last 15m to take the gold in 1:06.25 - 0.05 off the world record set by American teenager Jessica Hardy in Monday's semi-finals.
Hardy was in front at the turn but had to settle for second place in 1:06.62. Her compatriot Tara Kirk was third in 1:07.43.