Otago has two points and 8½ games after the four rounds and has already had its bye.
To ensure a place in the semifinals, Otago will have to perform well against Taranaki this morning and Wellington and Northland tomorrow.
It was a tough tussle in the morning against a determined Southland quintet and it did not get any easier against Canterbury in incessant rain in the afternoon.
In each of the South Island derbies, Otago posted two wins and a half. Michael Smith won both games while Brandon Hodgson and Chris Snow each had one win and a half.
No1 Fraser MacLachlan lost his morning game to Scott Hellier on the final green but he failed to keep in touch with Canterbury's Daniel Laughton in the afternoon.
No2 Brandon Hodgson had a tight battle against Southland's Matt Tautari and there was never more than one in it for the entire 18 holes.
However, Hodgson was forced to sink a 3m putt on the final green to secure the necessary half.
In the afternoon, he chipped in for a birdie-3 on the 17 hole to clinch the win at the expense of Canterbury's Matt McLean.
Inia Logan played Jeremy Hall in the morning round and fought back from an early deficit of three to trail by one with two holes to play.
However, he lost the 17th hole and Hall took the honours with one hole to spare.
In the afternoon, he came up against fellow New Zealand age-group representative Tom Parker and that was also a close tussle.
Logan was one down with three holes to play but Parker matched his birdie-3 on the 16 and took the match on the next green.
No4 Smith is the only Otago player to post three wins in the tournament beating Southland Leith Campion with a strong finish.
He lost the first hole to a birdie but, after squaring the match on the next hole, never looked like losing and eventually won the contest with two holes to spare.
In the afternoon, he was 2-down to Andrew Green after six holes but got back in contention with an eagle-3 on the seventh and a birdie-4 on the eighth.
The game then see-sawed but Smith found himself 2-down with four holes to play.
He won the 15th and 17th to get back to square and set up a birdie putt on the 18th to win the match.
Chris Snow had a tight match against Southland's Tegan Proudfoot but he forged ahead on the homeward run to win 2 and 1.
In the afternoon, he met 16-year-old Hiroki Miya and chipped in twice on the back nine for birdie-2s on par-3s.
But the Canterbury youngster was unfazed and the match finished all square on the final hole.
