Waikato bounced back from a one-point loss to Canterbury a week ago, beating Tasman 39-22 in a top-of-the-table NPC clash in Nelson on Friday night.
It marks the Mooloos first away win over the Mako in 14 years and snaps a seven-match losing streak against the defending champions.
Waikato spent 20 minutes with 14 men on the park after yellow cards to Steven Misa and Hamilton Burr within the first hour, but outscored the home side 32-10, scoring four tries to one.
The 17-point loss is just the fourth for Tasman since the start of the 2019 season and just the second at home in the same period.
The Mako were held tryless for 51 minutes before Leicester Fainga'anuku crashed over, but Waikato put the game to bed minutes later when halfback Cortez Ratima darted off the back of a scrum to run away and score from the 22.
Tasman had plenty of possession, but found resistance from a Waikato defence that made 160 tackles led by former All Black Liam Messam.
A late rally from Tasman gave some respectability to the scoreline but they were more than second-best on the night.
Waikato 39 (Lansdown, Coombes-Fabling, Wrampling, Ratima tries; Smith 4con, 2pen) Tasman 22 (Fainga'anuku, Frizell, Makalio tries, Hunt con, 2pen)
HT: 15-3
