Wellington avoided relegation by the skin of their teeth after edging past North Harbour 29-28 in Albany on Friday.
The win puts the Lions five points clear of bottom-placed Southland in the Premiership standings, which means the Stags drop to the Championship division next year no matter the outcome of their last match against Bay of Plenty on Sunday.
Composure in the second half and the pinpoint boot of pivot Lima Sopoaga were key facets in the win, which assured Wellington ITM Cup Premiership status for 2012.
The Lions came back from a 23-16 half-time deficit to score 16 unanswered points in the third quarter of play, before retaking the lead once more with about 10 minutes remaining after a fourth North Harbour try.
They then held off a frantic period of North Harbour attacking play in front of their tryline late in the match.
Sopoaga played a leading hand for Wellington, kicking seven attempts from seven including four second-half penalties.
His last penalty of the night from 45m out in the 71st minute put the Lions back in front after North Harbour wing David Raikuna had scored a try off a forward pass just moments before.
Now holding a one-point advantage, the Lions held firm to the end and fended off a 20-phase raid at the chalk by the home side.
For North Harbour:
Tries: Parsons, Smylie, Raikuna 2
Pens: Botica 2
Tries: Levave, Gear
Cons: Sopoaga 2
Pens: Sopoaga 5
Wellington: 15 Apoua Stewart, 14 Julian Savea, 13 Alapati Leiua, 12 Charlie Ngatai, 11 Hosea Gear, 10 Lima Sopoaga, 9 TJ Perenara, 8 Brad Shields, 7 Scott Fuglistaller, 6 Faifili Levave, 5 Mark Reddish, 4 Jeremy Thrush (c), 3 Neemia Tialata, 2 Dane Coles, 1 Reggie Goodes.
Replacements: 16 Motu Matu'u, 17 Jacob Ellison, 18 Joe Latta, 19 Dean Brunsdon, 20 Frae Wilson, 21 Michael Lealava'a, 22 Steve Honey, 23 Arden David-Perrot.
North Harbour: 15 Willie Walker, 14 Nafi Tuitavaki, 13 Rudi Wulf, 12 Brendon Watt, 11 David Raikuna, 10 Ben Botica, 9 Chris Smylie (c), 8 Mat Luamanu, 7 Scott Uren, 6 Solomon King, 5 Filo Paulo, 4 Anthony Boric, 3 Ben Afeaki, 2 James Parsons, 1 James Afoa.
Replacements: 16 Manu Leiataua, 17 Alex Woonton, 18 James King, 19 Brent Wilson, 20 Luke Hamilton, 21 Pita Ahki, 22 Codey Rei, 23 Taione Vea.