Southern produced a stout defensive effort to beat University A 11 5 and retain its position at the top of the standings.
Harbour had a 19-0 win over Zingari Richmond and remains in second place, while Taieri (third) banked a bonus point in its 33-13 win over Kaikorai.
Dunedin scored late to beat Alhambra Union 7-5 and moved back into the top four. Pirates crushed Green Island 31-0.
Southern 11
University A 5
Mud. Mud. Mud. The bleak conditions should have suited Southern's big pack but University A gave the competition leader a stern test in the Cavanagh Memorial at Bathgate Park.
The game was effectively played at one end with each team spending long periods camped in its own 22m and defending grimly.
Southern took the first shift. Classy University centre Matt Faddes made an early break on the right flank to get his side into prime attacking position and that is where the students stayed for the best part of 15 minutes.
Southern openside Dan Baxter helped ease some pressure with a fighting run. But it took a bruising run from massive prop Mike Mata'afa to set up the game's first points.
He shrugged off several tacklers before eventually being pulled down. The ball came out to the left and second five eighth Tei Walden made a deft pop pass to centre Nathan Cargo, who accelerated through a gap to score.
Faddes replied for University when he fended off his opponent and crashed over in the corner. The students crossed the paint twice more late in the half, but once there was a foot in touch and the second effort was ruled held up. It was gritty defence and Southern, through a Bryce Hosie penalty, led 8 5 at the break.
The game followed the same pattern in the second half but with the roles reversed. University's defence was equally as resolute. To concede just a penalty, given the weight of territory Southern enjoyed, was a credit to University.
Taieri 33
Kaikorai 13
Taieri got dominance up front and loose forwards James Lentjes and Charlie O'Connell ensured the battle for possession was tipped in the home side's favour at Peter Johnstone Park.
The 20 point buffer suggests a comfortable win but Kaikorai proved tenacious. It had good line speed and got up quickly to shut down Taieri's attacking forays. Its lineout was solid and, when under pressure, Kaikorai defended with passion.
But the Kaikorai scrum found reverse gear too often and that gave Taieri a base from which to launch. That allowed it to dominate possession and territory in the first half and it led 21-6 at the break.
Kaikorai got back to 21-13 when prop George Hendry scored following a melee close to the line.
But perhaps the turning point came when O'Connell beat several defenders and galloped 30m to score. Halfback Kurt Hammer had a strong game, making some darting runs. He used his strength to score late which earned Taieri a crucial bonus point.
Tony Ensor and Logan Moore were Kaikorai's best backs, while flanker Johnny Appleby and Hendry worked hard.
Taieri props Aki Seiuli and Nick McLennan also had impressive games.
Pirates 31
Green Island 0
A dominant Pirates pack paved the way for a comfortable win in bitterly cold conditions at Miller Park.
The Pirates pack dominated the scrum and was dangerous with driving play inside the Green Island 22m.
The key players in the pack were No 8 Josh Clark and lock Jared Williams with their barging runs with the ball and their work in the lineout.
All Pirates tries came after sustained drives by the pack inside the Green Island 22m. The other forwards to impress were props Craig Millar and Hisa Sasagi. The best backs were fullback Craig Sneddon with his long punts and centre Kenton Leiataua.
Pirates scored three tries and led 17-0 at the break after battling into the howling southerly wind. They added two more tries in the second half.
Green Island was beaten but not disgraced. The gutsy defensive effort into the strong wind in the second spell restricted Pirates to two tries.
There was more cohesion in Green Island's play than has been evident in earlier games this winter.
The best Green Island forwards were prop Hamish Finnie and No8 Steven Bradley. Replacement halfback Taylor Moeahu impressed with his passing in the second half.
Harbour 19
Zingari Richmond 0
The importance of retaining the Scoles Memorial Trophy was not lost on Harbour at Watson ParkFirst contested in 1955, the trophy, in memory of William James (Bandy) Scoles, is among the oldest premier interclub trophies in Dunedin, preceding the coveted Cavanagh Trophy by three years.
One player on Saturday with close links to the 61 year old trophy was Zingari Richmond winger Stephen Scoles, a great nephew of the player the trophy commemorates.
Scoles put in some superb defensive work down the left flank, playing in a position so desolate, wind blown and cold, even the penguins had deserted the outpost.
Scoles was well supported defensively by fellow outside backs Christian Walker, Taylor Fiddes and Enoke Nauvaluvalu in limiting Harbour's attack to its forwards.
The Harbour loose forward trio of Charles Elton, Hadleigh May and Ratu Dawai secured plenty of ball and played a big role in Harbour dominating territory for the greater part of the game.
Lock Elioti Tonga and prop Sekonaia T Pole worked tirelessly in securing and retaining ball at the breakdown.
Both halfbacks, Tala Fagasoaia for Harbour and Shaun Driver for Zingari Richmond, cleared the ball well in testing conditions and presented their respective sides with plenty of opportunity.
Dunedin 7
Alhambra Union 5
This was the classic game of two halves. Dunedin played with a gale at its back in the first half and it should have been worth 20 points.
But nobody showed the script to Alhambra Union, which controlled possession and territory for large chunks of the half.
The Alhambra Union forwards played with vigour and dominated the loose. Their pick and go game ate up large tracts of territory, and they were complemented by a backline that tried to give the ball air at every opportunity.
Alhambra Union was rewarded with a try to Tili Puloka after 25 minutes, while Dunedin missed two easy penalties and kicked the ball dead three times.
The Dunedin pack took control in the second half. Its scrum was completely dominant with three tightheads, and its continuity was superb.
Alhambra Union lost two players to the bin towards the end of the game, and right on fulltime, hooker Aiden Lloyd burrowed over and Greg Dyer converted to give Dunedin the win.
Mark Grieve Dunn was a colossus for Dunedin, and Lloyd and Donald Brighouse led the powerful scrum. Hame Toma and Danny Underwood were glued to the loose ball in the second half.
Peter Breen, in his 100th game for Alhambra Union, showed some classy touches in trying conditions. No 8 Lance Barbarich was aggressive, Tom Frood battled away in the loose and Caleb Gray was competent behind a beaten pack.
Two things demonstrated the power of the elements. Breen attempted a kick from 65m that had the distance but not the direction, and replacement Dunedin halfback Luke Donaldson threw a pass to his pivot which went dead 60m away.
