Williams Formula 1 development driver Jamie Chadwick just snatched pole for the inaugural W Series championship finale at Brands Hatch, while her title rival Beitske Visser qualified fifth.
Chadwick set a blistering time of 1m22.425s in the final minute of qualifying, deposing Alice Powell who had looked assured of pole until the final moment.
The session began with Visser setting the benchmark time of 1m27.205s, but she quickly dropped through the order as far as seventh as the laptimes started to gather pace as the session wore on.
Visser was initially deposed by Emma Kimilainen at the top, whose time was then subsequently beaten by Chadwick's early efforts - with Powell then joining the fray as the three drivers traded provisional pole between themselves.
Around the midway point of the session, Chadwick peeled into the pits for a change of tyres, leaving Powell and Kimilainen to fight it out - a margin of just five thousandths of a second separating them at one point.
Powell's late attempt of 1m22.793s looked like the fastest time of the day, before Chadwick's final effort just before the chequered flag ultimately gave the championship leader her third pole of the season as she heads into Sunday afternoon's title decider with a 13-point advantage over Visser.
Porsche Carrera Cup GB driver Esmee Hawkey impressed with her best qualifying performance yet to set a time for third, ahead of Kimilainen whose last-gasp tries for pole were thwarted when she ran through the gravel at the entry to Westfield.
Fabienne Wohlwend will line-up behind Visser in sixth - although had also been fighting for the front four grid positions - with Miki Koyama seventh and Sarah Moore eighth after another late improvement.
Jessica Hawkins ended the session in ninth, with former GP3 racer Vicky Piria completing the top 10.
Both Hawkins and Piria are in a fight for 12th position in the overall championship, which will ultimately determine whether they are guaranteed to return to the W Series grid in 2020.
Piria is currently in danger in 10th, while Hawkins needs a strong showing at Brands Hatch to elevate her from 14th.