Nathan McCullum’s half-century helped Otago Volts to a 200-plus lead over Northern Knights at Hamilton’s Seddon Park.
Northern declared on 328 for eight, once first-innings points had been attained, with Otago attempting to set up a lead to defend.
Daniel Flynn’s century and 43 from Peter McGlashan put the champions in sight of their target.
Otago moved to 211 for six at stumps, McCullum leading the way with 53 not out.
With one day remaining, both sides require outright victory to continue their push to reach next month’s final.