Adlington broke Sarah Hardcastle's British record in the heats
Rebecca Adlington and Cassie Patten secured the two qualification places for the 800m freestyle at the British Olympic trials in Sheffield.
Adlington, already qualified for the 400m, stormed ahead and was on course to beat her own Commonwealth record.
She just missed out but won the race in eight minutes 20.29 seconds from open water specialist Patten, who clocked a personal best time of 8:29.83.
Jo Jackson and former world medallist Rebecca Cooke were third and fourth.
With Adlington so far ahead, the main battle was for second place and Derwentside's Jackson appeared to have the measure of Stockport Metro's Patten.
She was ahead at the 500m stage but Patten overhauled her at 600m and it was her stamina that proved decisive as she took the key second spot.
I got a little bit excited and went out faster than usual but I've got to learn to do that and get it right
Jackson took the bronze medal in a time of 8:38.05.
Adlington, who became the sixth fastest swimmer of all time over 800m in Thursday's heats, was understandably in positive mood after another victory.
"That felt really painful," she said. "It hurt a lot but I'm so happy with that time. It's still five seconds ahead of where I was before this meet.
"I have a great coach who knows how to get the best out of me and it has been a great week for me.
"I want to better the times I have done in Beijing."
For close friend Patten, more accustomed to much longer races, it was a welcome surprise and she admitted: "I was only going for the open water so this is something else."
But former world championship bronze medallist Rebecca Cooke will not be travelling to China, however, after finishing fourth.
"I gave it my best shot and that is all I can do. I don't have any regrets," said Cooke.
Lizzie Simmonds earned her second qualification of the week when she edged out Gemma Spofforth in the women's 200m backstroke.
Simmonds was around a second ahead of her nearest rivals at the halfway point, but Spofforth, who won the 100m backstroke, closed in on her in the final 50m.
But it was 17-year-old Simmonds who took the gold medal with a time of 2:08.99, with Spofforth forced to settle for second place in 2:09.70 and Stephanie Proud third in 2:11.10.
"I got a little bit excited and went out faster than usual but I've got to learn to do that and get it right," Simmonds said. "It wasn't my best swim but I'm in there now."
Meanwhile, Ross Davenport failed to add the 100m freestyle title to the 200m he won earlier this week after losing out to Ben Hockin, with Adam Brown and Commonwealth record holder Simon Burnett in second and third.
Burnett will not be travelling to Beijing after failing to qualify in any of the individual events, while his hopes in the 4x100m relay have also vanished.
The British men failed to qualify for the freestyle relay because the top four times from the final in Sheffield - when added together - needed to be inside the Olympic qualifying time, but the swimmers were 0.9secs too slow.
Beijing qualifiers to date:
*Already nominated to Team GB by British Swimming
*David Davies - 1500m freestyle
*Liam Tancock - 100m backstroke, 200m individual medley
Mark Foster - 50m freestyle
Gregor Tait - 100m backstroke, 200m backstroke
David Carry - 400m freestyle
Dean Milwain - 400m freestyle
James Goddard - 200m individual medley, 200m backstroke
Chris Cook - 100m breaststroke
Kristopher Gilchrist - 100m breaststroke, 200m breaststroke
Ross Davenport - 200m freestyle
Robbie Renwick - 200m freestyle
James Kirton - 200m breaststroke
Thomas Haffield - 400m individual medley
Euan Dale - 400m individual medley
Michael Rock - 100m butterfly
Todd Cooper - 100m butterfly
*Kirsty Balfour - 200m breaststroke, 100m breaststroke
Caitlin McClatchey - 100m freestyle
Fran Halsall - 100m freestyle, 50m freestyle, 100m butterfly
Julia Beckett - 100m freestyle (relay)
Jessica Sylvester - 100m freestyle (relay)
Jemma Lowe - 200m butterfly, 100m butterfly
Ellen Gandy - 200m butterfly
Rebecca Adlington - 400m freestyle, 800m freestyle
Jo Jackson - 400m freestyle
Gemma Spofforth - 100m backstroke, 200m backstroke
Lizzie Simmonds - 100m backstroke, 200m backstroke
Hannah Miley - 200m individual medley
Keri-Anne Payne - 200m individual medley
Kate Haywood - 100m breaststroke
Cassie Patten - 800m freestyle