A missed tackle from Northland B in the dying stages allowed Counties Manukau B to score the match-winning try despite trailing at half time.
The visitors won 30-27 at Okara Park, Whangārei in a match preceding the Northland v Auckland Mitre 10 Cup clash on Sunday.
Counties took advantage of the hosts' poor discipline and sloppy defence and raced to a 17-0 lead inside the first quarter before Northland B found their mojo and hit back with three tries before halftime.
It wasn't until the 32nd minute before Northland B wing Renata Roberts-Tenana opened the scoring for the home side.
Fijian Tavite Gadeisuva fielded a clearance kick on his 10m line before flinging a pass to Roberts-Tenana who jinked his way past a number of Counties defenders and bolted 40m to score.
Northland B struck five minutes later when first five Wiseguy Faiane threw a dummy pass and set up Tim Blundell to touch down for the team's second try.
Halfback Mac Sykes stretched off a ruck and planted the ball on the tryline after a brilliant interchange between him, Gadeisuva, and openside flanker Jarod Byrnes on the left flank.
Northland B led 21-17 at half time.
Ill-discipline crept back in for the home side after the breather and the team conceded three penalties in quick succession for holding on to the ball, wheeling the scrum and a shoulder charge.
Counties B halfback Liam Daniela was sent to the bin for a tip tackle on Faiane who hobbled off the field not long after.
The visitors scored in the 60th minute when reserve lock Damon Leasuasu bumped off two tacklers before thudding the ball on the tryline as if to make a statement.
His team took the lead 25-24 but Blundell kicked a penalty for Northland B to take back the lead which was short-lived.
Levi Clark berated himself when he missed a tackle on his opposite Sione Fifita, who beat him on the outside to race away for the match-winning try nine minutes from fulltime.
Northland B tried every trick in the bag, even opting for lineout rather than a kick at goal when Counties B players were penalised for offside play.
A late surge on the visitors' 22m by Northland B No 8 Sam McNamara proved futile after he knocked the ball in a tackle.
All Counties B had to do to win the game was kick the ball into touch from a dominant scrum and they did.