Southland posted a shaky 41-6 win over Counties- Manukau at Pukekohe while Bay of Plenty recovered from last week's loss in Invercargill with a 24-13 home win over Tasman.
Southland have 28 points, three clear of Bay of Plenty, but Canterbury will regain the lead if they retain the Ranfurly Shield in tonight's match against Taranaki.
Although Southland was expected to easily beat Counties-Manukau, the visitors scored only one try in an error-riddled match.
There were some good patches of running rugby in Mt Maunganui where the home side scored three tries to one.
But it was fiery at times, too, with three players sin-binned within a few minuites late in the first half which ended with Bay of Plenty ahead 7-3.