Stacie Powell upset her more fancied rivals to qualify first for the women's 10 metre platform final at the British Gas Diving Championships in Sheffield.
Powell, an astrophysics student at Cambridge University, outshone star names Tonia Couch and Monique Gladding to put herself in pole position for Saturday evening's Olympic qualifier.
The winner of the final will earn a direct place into the Games team, with a British Diving selection panel to announce a second diver on Monday.
Beijing Olympian Couch and Gladding had looked the most likely contenders for a direct berth, but they were unable to crack the top-three to underline the depth of talent in women's platform diving.
Couch had to be content with fourth, behind synchro partner Sarah Barrow and Jenny Cowen, with Gladding scraping into the final in seventh.
"I wasn't really paying attention to what everyone else was doing," said Powell, who finished eighth at last month's European Championships in Eindhoven.
"I just wanted to show the others in this meet that I was still around and that I'm still there. They've got to watch out."
Earlier, Jack Laugher produced a personal best 480.80 to stamp his class on the men's 3m springboard ahead of Saturday night's final.
Chris Mears, who claimed victory in the 3m synchro on Friday, was almost 50 points behind Laugher in second.