St Clair accounted for Taieri at Taieri 4.5-1.5 on Saturday and posted a resounding 6-0 win over Otago Gold in a catch-up game at home on Sunday.
St Clair's successful weekend puts it at nine points with 16.5 games at the halfway stage of this year's series.
Otago Blue remains unbeaten with four wins, 12 points and 19 games to lead after some emphatic wins.
St Clair notched four wins over Taieri, with Brent McEwan, Tony Giles, Stephen Hitchcox and Stephen Hitchcox all successful.
At No 3, Brian Shaw was the only Taieri golfer to win, beating Chris Snow on the final green.
Taieri looked set to post a second win, with Mark Andrews 3-up on Hitchcox with five holes to play, but Hitchcox won 14 and 18 with pars and 15 and 16 with birdies to turn the tables and win on the final green.
Meanwhile, Otago Blue was too strong for Chisholm Park, as No 1 Nick Borren, No 2 James Anstiss , No 4 Sean Masters and No 5 Jason Hughes posted impressive wins.
Borren was under par, beating Mark Collie in 15 holes, while Anstiss eagled 9 and 11 and posted five birdies to give Park's seasoned campaigner, Kyle Geary, little chance.
At No 6, Antony McCullough returned to the team, beating Tony Ruddenklau to give Chisholm Park its only win.
The tight match was between Tyrone Ratahi and schoolboy Conor Jamison.
Ratahi birdied the final hole to give Otago Blue its fifth win.
In the catch-up game, Otago Gold was little match for the top St Clair sextet, which blooded two new players for the encounter.
Ryan Bellamy (Port Chalmers) and Michael Ormandy (North Otago) have joined St Clair and posted wins over Gus Rattray and Jodin Johnson, to give St Clair a decisive winning margin.
