European champion Fran Halsall set the fastest 100m freestyle time of the year on the way to becoming number one in the event's world rankings.
She recorded 53.57 seconds at the British Swimming Championships, which double as a qualifier for this summer's Olympics and Paralympics.
The 21-year-old from Southport will be joined in the event at the London Games by Loughborough team-mate Amy Smith.
"It's a really good time for me right now," Halsall told BBC Sport.
"To be just off my world championship time of last year, four months from the Olympics, makes me really happy."
Halsall, who qualified for London 2012 in the 100m butterfly earlier in the week, was just two one-hundredths off world-record pace at the halfway point.
"I think if you want to swim fast, you have to go out fast but my new suit helped me on the way back and it will later in the year," said Halsall.
Smith set a personal-best-time of 54.01 seconds and herself rose to number three in the global standings.
She said: "It helped having her [Halsall] there, because she's done so well to claim that time and it's great to race people like that at the British Championships.
"I'm over the moon because qualifying for the Olympics is all I've ever wanted to do and to manage that in the individual as well as the relay is great."
In the men's 200m individual medley final, Commonwealth champion James Goddard was the favourite but he was edged out in a tight finish by Joe Roebuck, who completed an incredible few days by qualifying for a third Olympic event.
"It's been a fantastic week for me," Roebuck told BBC Sport.
"It was great going into the race knowing I had two [Olympic] places, but it wasn't job done because I still wanted this event and I would have been disappointed if I hadn't qualified in this."
Goddard, who decided not to race in his favoured event - the 200m backstroke - to increase his medal chances in the 200m individual medley, added: "If I want to compete with [Ryan] Lochte and [Michael] Phelps I have to go quicker, but come the Olympics I'll be better."
Stacey Tadd became the 21st British swimmer to confirm an individual place at the Olympics by claiming victory over 15-year-old Molly Renshaw.
"I'm absolutely amazed and so relieved that's over," said Tadd.
"I can't explain how nervous I've been, pacing around all day just thinking about it, but now I've done it."
Less than two-tenths separated the swimmers, but while Tadd's 2:26.63 was enough to reach this summer's Games, Renshaw will have to return for the second trials in Sheffield in June.
"I'm a bit gutted, but I can come back and try again. I could have pushed it more at the start so I'm a bit disappointed," said Renshaw.
In the men's 200m backstroke final, Calum Jarvis claimed a surprise win over Marco Loughran and Chris Walker-Hebborn, but none of the swimmers achieved London 2012 qualifying times.
Olympic champion Rebecca Adlington will headline day seven of the championships in the 800m final, alongside Keri-Anne Payne, Hannah Miley and Eleanor Faulkner.
One swimmer who will not contest an Olympic place in the event is Welsh-record-holder Jazz Carlin, who has withdrawn with an illness.
The 19-year-old, who was diagnosed with glandular fever last year, has endured a difficult week, missing out on Olympic qualification in both the 200m and 400m freestyle.
British Swimming say Carlin will now return home to Swansea for treatment.