Wellington advanced to the semifinals of the HRV Cup with a win over Northern Districts today - and Auckland could join them there with one more victory.
With Otago having already clinched top spot and secured a home final for Sunday, four teams entered today with a chance of making Friday's semifinal.
Wellington wrote their ticket with a tense victory at the Basin Reserve, while Auckland eliminated Canterbury in Rangiora and now have a chance of edging ND to the final playoff spot.
Auckland will need to beat last-placed Central Districts in their final match at Eden Park on Tuesday, and they will need to do it in comprehensive fashion to overtake the Knights on run rate.
Both of today's matches with playoff implications went to the final over and, while Northern Districts failed to chase Wellington's 181, Auckland overhauled Canterbury's 182 with three balls and four wickets to spare.
The hero for the Aces was South African-born allrounder Donovan Grobbelaar. The 29-year-old, enjoying his maiden season of first class cricket, came to the crease with his side needing 27 from the final 14 balls.
Grobbelaar promptly took 16 runs from three Andrew Ellis deliveries in the penultimate over, before winning the game with a boundary off Logan van Beek to finish unbeaten on 24 from just seven balls.
The result appeared unlikely earlier in Auckland's chase, but Colin de Grandhomme (36 from 23) and Craig Cachopa (37 from 25) combined for a fifth-wicket partnership of 73 from 41 balls.
That set the stage for Grobbelaar to overtake Canterbury's challenging target, set up by opener George Worker's 89 from 60 balls.
In Wellington, ND weren't able to match the northern neighbours' second-innings success, with Australian Theo Doropoulos making an immediate impact in his first game for the Firebirds.
Wellington Cricket had announced before the game they had secured the services of an import without revealing the player's identity. When Doropoulos took his place in the middle there was a hint of an anti-climax from a crowd hoping for someone of Chris Gayle's ilk, but the Western Australian more than made up for any disappointment.
The Knights needed 16 runs from the final over but Doropoulos allowed just six and took a wicket from the last ball to finish with figures of 3-24 from his four overs.
His death bowling denied ND captain James Marshall from seeing his side home, with the batsman left stranded on 53 from 27 balls. His innings was the only reason the Knights were able to get close to Wellington's total, built on the back of an unbeaten second-wicket stand of 142 runs.
Jesse Ryder, by his own considerable standards, was relatively sedate in his innings of 85 from 65 balls, but his combination with Michael Papps (65 from 42) was the winning of the match.
In the day's other game, Otago kept up their eight-match winning streak ahead of Sunday's final by chasing down CD's 163 with three wickets and four balls in hand.
