Tasman broke a six-game ITM Cup losing streak after beating Bay of Plenty 41-39 at Lansdowne Park in Blenheim on Sunday.
It was only the Makos third win of the season and lifted them a place to twelfth on the table, while Bay of Plenty - ending with two bonus points from the upset loss - slipped a spot to seventh.
The Steamers scored six of the nine tries and overcame a 19-point deficit in the final quarter to take a one-point lead (39-38), before Tasman full-back Tom Marshall slotted his eighth penalty goal near the end to seal the game for the Makos.
Tries: Poki, Christie, Malneek
Con: T Marshall
Pens: T Marshall 8
For Bay of Plenty:
Cons: Delany 3
Tasman: 15 Tom Marshall, 14 Kade Poki, 13 Afeleki Pelenise, 12 Jack Umaga, 11 James Kamana, 10 Robbie Malneek, 9 Steve Alfeld, 8 Poutasi Luafutu, 7 Shane Christie, 6 Glen Gregory, 5 Chris Jack (c), 4 Anthony Elisala, 3 Ben Franks, 2 Vernon Fredericks, 1 Sam Prattley.
Replacements: 16 Francis Smith, 17 Fai Mika, 18 Ben Coman, 19 Jonathon Poff, 20 Kaide Whiting, 21 James Marshall, 22 Sione Holani.
Bay of Plenty: 15 Ben W Smith, 14 Lelia Masaga, 13 Brett Mather, 12 Corey Aporo, 11 Jason Hona, 10 Mike Delany, 9 Taniela Moa, 8 Colin Bourke (captain), 7 Tanerau Latimer, 6 Luke Braid, 5 Culum Retallick, 4 Luke Andrews, 3 Tristan Moran, 2 John Pareanga, 1 Josh Hohneck.
Replacements: 16 Daniel Perrin, 17 Joe Savage, 18 Aiden Kuka, 19 Solomon King, 20 Chad Tuoro, 21 Daniel Waenga, 22 Grant McQuoid.
Referee: James McPhail