Waikato ripped the Ranfurly Shield from Taranaki's grasp after thumping their hosts 46-10 at Yarrow Stadium in New Plymouth on Wednesday.
The Amber and Blacks, firm favourites to hold on to the Log O'Wood for the second consecutive season, were no match for the Mooloos who outscored the home side seven tries to one with wing Tim Mikkelson bagging a hat-trick.
The crucial victory for Waikato (their fourth win from eight games) lifts last year's finalists from a three-way relegation battle with Bay of Plenty and Hawke's Bay - leaving them five points outside the top four.
The Mooloos will have to see off the challenge of Hawke's Bay next weekend to ensure the Shield stays in Hamilton and have a clash in Pukekohe against the impressive Steelers this weekend as they fight to stay in the top division.
Taranaki will try and bounce back as they look to advance through the finals, with their final regular season fixtures coming against Southland and Wellington.
Tries: Cummings-Toone, Bradley, Christie, Mikkelson 3, Renata
Cons: Renata 4
Taranaki: 15 Kurt Baker, 14 Andre Taylor, 13 Willie Rickards, 12 Jayden Hayward, 11 Frazier Climo, 10 James Marshall, 9 Jamison Gibson-Park, 8 Blade Thomson/Kane Barrett, 7 Chris Walker, 6 Jarrad Hoeata, 5 Jason Eaton, 4 Craig Clarke (capt), 3 Michael Bent, 2 Laurence Corlett, 1 Chris King.
Replacements: 16 Timo Tutavaha, 17 Carl Carmichael, 18 James Broadhurst, 19 Kane Barrett/Blade Thomson, 20 Bernie Hall, 21 Brett Goodin, 22 Jack Cameron.
Waikato: 15 Trent Renata,14 Declan O'Donnell, 13 Save Tokula, 12 Jackson Willison, 11 Tim Mikkelson, 10 Sam Christie, 9 Tawera Kerr-Barlow, 8 Alex Bradley (c), 7 Zak Hohneck, 6 Matt Vant Leven, 5 Sam Kilgour, 4 Romana Graham, 3 Ben May, 2 Marcel Cummings-Toone, 1 Toby Smith.
Replacements: 16 Vance Elliott, 17 Latu Talakai, 18 Anthony Wise, 19 Rory Grice, 20 Brendon Leonard, 21 Piers Francis, 22 Joe Webber.