Northern Districts all but wrapped up the Plunket Shield when completing a 10-wicket win over Auckland at Cobham Oval in Whangarei by the third evening on Sunday.
Auckland finished only five runs in front of ND's first innings total, a target knocked off in one over by BJ Watling and Brad Wilson.
ND has 44 points with Otago on 26, facing a huge target of 435 to beat Canterbury, and Central Districts which should beat Wellington early on the fourth day, also on 26 but facing a huge task to overhaul ND at the post.
ND extended its first innings advantage over Auckland to 183 largely due to another outstanding contribution by teenaged batsman Kane Williamson. He scored 192 in a Marathon innings of 463 minutes during which he hit 22 boundaries and two sixes, completing a neat century in boundaries.
It surpassed his previous highest score of 170 and was his fourth century in his 18-match career. He added 109 for the eighth wicket with Peter McGlashan, who scored 44.
Auckland employed nine bowlers in the bid for a breakthrough with Michael Bates taking 2-53 from 27 overs while Gareth Shaw had 2-88 and Colin de Grandhomme 2-44 while Anaru Kitchen's seven overs produced 2-31.
Auckland suffered a top and middle-order collapse as Graeme Aldridge claimed Jeet Raval, Richard Jones, Reece Young and Anaru Kitchen to leave it reeling at 52-4 and two more wickets fell to leave it at 68-6. Shaw hit 28 to get the score through to 131 but he fell to Williamson's off-spin and it was left to Michael Bates with 51 to require ND to bat again, albeit for six runs.
Aldridge had 4-19 off 13 overs while Williamson took 3-48 from 10 overs.
Wellington failed to build on its 18-run lead over Central Districts at the Basin Reserve when dismissed for 207 in its second innings. Neal Parlane proved the only significant contributor for Wellington when scoring 90 in batting for 349 minutes. Luke Woodcock's 29 was the best of the rest of the batsmen.
Captain Matthew Bell batted at No.10 as the result of a broken finger and still managed 15.
Doug Bracewell completed a fine match with four wickets for 49 runs to go with his first innings haul of five wickets.
Central Districts made light of its target of 226 runs and in 37 overs, it had scored 172-2, 54 runs short of the required total.
Otago scored 221 to be 94 behind Canterbury on the first innings in Queenstown. Derek de Boorder ending on 55 and Chris Martin taking 3-52 and Hamish Bennett 3-60.
Canterbury rattled on 340 in 89 overs thanks to Michael Papps' 122, his second century of the season and the 18th of his career. Johann Myburgh scored 90 with Dean Brownlie adding 25, Kruger van Wyk 28 not out and Todd Astle 31 not out. Warren McSkimming took 2-41 for Otago.
With a huge target of 435, Otago has never chased 400 to win a first-class match, Otago was 19 without loss at stumps.