The Saints pipped the Dunedin Golf Club 4-2 at Chisholm Links.
The clash was transferred to the beach as the Otago Golf Club’s Balmacewen course closed in the inclement conditions.
St Clair got wins out of the top three spots in the order.
No 1 Parker Aluesi was 1-up heading to the 18th against Blair Liffiton when he drove the green and made birdie to seal a 2-up win.
Tony Giles beat youngster Kai Koni 3/1, and Connor Howes romped to a 6/5 win over John McIntee.
Jason Pegler pulled one back for Dunedin GC, beating Cam Botting on the last hole, and Mike Weastell scored the home side’s other point with a 5/4 win over Logan Clarke at No 6.
Albert Reed sealed the win for the Saints by beating Mackenzie Gibson 3/2 at No 5.
The all-Otago clash between the Bombers and the B52s was also shifted to Chisholm Links.
The Bombers won 4-2.
Ryan Rosevear pipped Brian Helton 1-up at No 1, and the No 2 clash between Luke Murdoch and Harrison Maaka ended all square.
The No 6 clash between Duncan Croudis and Jonty Smith could also not be split, so the middle order would determine the tie.
Brandon Hodgson nabbed a point for the Bombers with a 3/2 win over George Prendergast, Lewis Harper pocketed one for the B52s with a 5/4 win over Hayden Coutts, and Bombers veteran Ben Patston sealed it with a 2/1 win over Jackson Hughes.
St Clair finished top of the table on 19 points with a 31-17 win-loss record.
Dunedin and the Bombers each ended with 16 points, Dunedin earning second spot for the semifinals with 28.5 wins to 26.
St Clair will host the B52s in one semifinal this Saturday, while Dunedin will host the defending champion Bombers in the other.
