Northland made eight changes to the side that thrashed Otago on Wednesday night, but the tail end of what may still be considered a successful roadtrip, caught them in extra time.
There was little to separate the two sides throughout the 80 minutes. Both sides looked likely to score whenever they ran the ball, and attack triumphed over defence.
Five of the eight tries were made from slick backline running and Southland winger Keanu Kahukura particularly caught the eye with a classy double.
Northland led by two points at halftime, then kicked their way back into a five-point lead with nine minutes to go.
Their forward pack defended for their lives in the dying stages and looked to have the points sewn up, before one final desperate burst from the Southland attack burst the dam.
Southland: 36 (Keanu Kahukura 2, Mark Jackman, Tim Boys, Lolohea Loco tries; Lima Sopoaga 1 pen, 4 con); Northland: 34 (Matt Moulds, Matt Wright 2 tries; Daniel Hawkins 2 con, 5 pen). HT: 15-18.