A last-gasp try from Toa Halafihi sealed a dramatic 35-32 victory which earned Taranaki a home Mitre 10 Cup semi-final and left Auckland's fate out of their hands.
Down to 14 men for the closing stages after Declan O'Donnell was sin-binned, Taranaki looked to be heading for defeat at Yarrow Stadium until the forwards cranked up the pressure and Halafihi barged his way over following a scrum five metres out.
The victory for Taranaki in New Plymouth guaranteed them second spot, but last year's runners-up Auckland could now miss out on a place in the last four to Counties Manukau and Tasman - who are both in action at the weekend.
Auckland led 19-13 at half-time following a brace of tries from Rieko Ioane and a Melani Nanai score, but paid the price for indiscipline after the interval.
They held a slender 32-28 advantage with seven minutes to play after Simon Hickey added the extras following a penalty try, with converted scores from Rhys Marshall and Ben Matwijow having previously put Taranaki in front.
Taranaki were not finished yet, though, and number eight Halafihi came up with the decisive try, which Marty McKenzie converted to take his tally for the match to 15 and prolong the home side's season.