Auckland are on 85 competition points, 14 ahead of Canterbury, with Gary Stead's side climbing into second with an eight-wicket win over Northern Districts.
Canterbury were left requiring 89 to win after they wrapped up Northern's second innings for 316 early on day four. Bharat Popli's 94 was the highlight for ND as Canterbury cruised to victory with well over a session to spare.
Canterbury leap-frogged Wellington on the ladder, after they fell to Central Districts by 87 runs.
Set an unrealistic 369 to win in just over two sessions, Wellington's top order fought hard through Luke Woodcock (63), Stephen Murdoch (82) and Luke Ronchi (88).
However, a middle order collapse spearheaded by spinners Ajaz Patel (4-103) and George Worker (4-58) saw none of Wellington's bottom six reach double figures.
Tailenders Matt Bacon and Brent Arnel held out for seven overs, but with time ticking down Worker struck late to give CD their first win of the season.
Plunket Shield ladder
Auckland 85
Canterbury 71
Wellington 67
Northern Districts 49
Central Districts 48
Otago 42
Top runscorers
1 Bharat Popli 679
2 Brad Wilson 646
3 Ben Smith 628
4 George Worker 575
5 Stephen Murdoch 530
6 Luke Woodcock 489
7 Neil Broom 485
8 Luke Ronchi 454
9 Michael Papps 429
10 Michael Guptill-Bunce 423
Top wicket takers
1 Scott Kuggeleijn 33
2 Ish Sodhi 22
2 Jeetan Patel 22
4 Jimmy Baker 21
5 Ajaz Patel 20
5 Brent Arnel 20
5 Dane Hutchinson 20
5 Todd Astle 20
9 Blair Tickner 18
9 Donovan Grobbelaar 18
