The Magpies used their formidable scrum to set up a 36-23 win against Dunedin at Bathgate Park. It was like death by scrum for the Sharks.
Harbour is also unbeaten after three games. It dispatched Zingari-Richmond 54-17 at Montecillo.
The Hawks ran in eight tries, many of them quite spectacular.
But Green Island has also emerged as a genuine threat. It beat Kaikorai 43-29 thanks to some tough defence in the first half and direct running in the second.
Taieri had too much firepower for Alhambra-Union, winning 43-20 at Peter Johnstone Park.
Green Island 43 Kaikorai 29
Green Island bears no resemblance to the side which was stuck jostling with Zingari-Richmond and Alhambra-Union at the bottom of the standings for years.
This team is in the top four and does not look like dropping out any time soon.
The Grizzlies beat Kaikorai 43-29 and did it using the full bag of tricks. The home team spent almost all of the first half pinned in its own 50 and desperately holding on.
It strung together too many errors, to be fair. But feisty loosehead Shane Fikken barrelled over late in the half to level the score at 7-7.
Kaikorai pivot Ben Miller drilled a penalty before the break to return his side to the lead. But Green Island turned with the wind at its back, and it made much better use of the breeze.
First five-eighth Finn Strawbridge kept the ball in front of his forwards. And impressive second five-eighth Raymond Nu'u made a tremendous impact off the bench.
He sliced through to score and made another break to set up Yonhi Kim.
When hooker Jake Lane-Fowler reached through the ruck to score the first of his two tries, Green Island had put on 26 unanswered points.
The game looked over, but Kaikorai responded with some carefree rugby. Outside back Matt Jones bagged a double within a couple of minutes.
But all hope was snuffed out when Lane-Fowler crashed over from a lineout drive. Kaikorai rescued a bonus point with a late try.
Taieri 43 Alhambra-Union 20
Taieri ran in two late tries to secure a 43-20 win against the winless Alhambra-Union.
But the Broncos were more competitive than the final margin suggests.
It was a memorable match for Eels halfback Bob Martin. He had nabbed three tries before the halftime whistle.
He was electric around the ruck and helped make the difference. He also set up prop Ethan Harrex for one of the tighthead's two tries with a 40m break.
Martin left partway through the second half with an injury, though.
Taieri led 33-15 at halftime, but Alhambra-Union kept battling and had its moments. It can take some heart out of the performance.
The side has lost all three games this season, but got across the line for three tries.
Its forward pack certainly had parity and fullback Levi Emery produced another strong performance. He was threatening on the counterattack and has plenty of gas.
He also scored a nice try and landed a conversion and a penalty.
Perhaps the biggest flaw in Alhambra's game was it was caught napping at crucial times.
It conceded a try in the first minute of the game, another just before the halftime break the two late five-pointers.
A few mental lapses aside, it was an even contest. There was a lot of ball movement and endeavour from both sides. There were mistakes but it was an entertaining game.
Taieri's lineout was a little wobbly. But with seven tries to three it can take plenty out of the game as well.
Southern 36 Dunedin 18
A dominant tight five wins games is the adage, and this was truly personified by the Southern scrum. At Bathgate Park, Southern had the Dunedin scrum back-pedalling at a rate of knots all day, and this was difference between the sides.
Three of Southern's tries came from scrums or scrum penalties, and the scrummage also cost Dunedin a man in the bin.
Southern got the early try off a weak Dunedin defensive clearance and Mackenzie Haugh showed his pace. Southern had the bonus point by halftime and the game was over for the Sharks.
Dunedin did not have much to show for its first half effort apart from two George Witana penalties, until prop Sepa Vaka crashed over in the final play of the spell.
Southern scored early in the second spell from a pushover try to Sam Pene when Dunedin was down to seven forwards. Winger Owen Draper then scored from a cross kick from Dominic Clapcott to put the game out of sight.
Dunedin hit back late in the game with tries to Witana and Vaka, the latter bagging his second to add some respectability.
Apart from their superior tight five, the Southern midfield terrorised the Dunedin backline, whose flimsy defence was porous at best.
For the Magpies, Hisa Sasagi, in his last game before his ``Singapore sling'', was immense at prop and single-handedly demolished the Dunedin scrum. Lock Caleb Grace won enough lineout ball and Pene was solid at the back of the scrum. Midfielder Kalolo Tulifauomanaia was the game's best back and Draper and Haugh were dangerous out wide. Sasagi, though, left the field was leg injury late in the game.
Dunedin prop Sepa Vaka was lively on the carry. Winger Keegan Christian Goss was mistake-free out wide and carried strongly. Replacement halfback Devon Oliver-Bell added zest and spark when he came on late in the game.
Harbour 54 Zingari-Richmond 17
Here is a tip.
Do not kick the ball back to Harbour.
The joint defending champion is lethal on the counterattack and from broken play.
Experienced fullback Sala Halaleva really knows how to get something going when he is out in the open.
He combined with centre Aleki Morris-Lome to shred the Zingari-Richmond defence all too often. Neither dotted down for any of the eight tries Harbour scored in its 54-17 victory.
But Morris-Lome was so influential. He was rock-solid on defence and got to the gain line or over all almost every time he carried.
He deserved to score a try. He ran about 40m in search of one but was cut down in the corner.
Morris-Lome also did a good job setting up his outside backs, while lock Isaiah Mapusua led an impressive effort by the side's engine room.
He was reliable in the lineout and tidied up a lot around the paddock.
The Hawks are not showing any early weaknesses, that is for sure. They played some scintillating rugby and scored some wonderful tries. They led 21-10 at the break. But when the game opened up in the second half, Harbour was threatening from anywhere.
For the colours, Shaun Driver had a decent match at first five-eighth. He steered his side around as best as he could and tried desperately to get his outside backs going.
But Harbour was just too big, too powerful and too quick. Hard to compete with that.
- ODT rugby writers