Defending champions Waikato Chiefs made a timely return to the top of the Super 15 standings with a bonus-point 34-22 New Zealand derby win over Wellington Hurricanes this weekend.
Northern Bulls, who have worn the southern hemisphere provincial crown three times, were also bonus-point winners as they scored six tries in a 48-18 romp over fellow South Africans Southern Kings and rose to second spot.
Australian outfit ACT Brumbies, inactive because of the Wallabies Test series against the British and Irish Lions, slipped two places to third on the combined standings.
Chiefs (61 points), Bulls (59) and Brumbies (59) are assured of top-six slots and tickets to the knockout stage of a competition Waikato won at a canter last year with a 37-6 thumping of South African visitors Coastal Sharks.
The top-two finishers dodge the first play-off phase and secure semi-finals places, and the odds favor Chiefs and Bulls because they have two fixtures to play, while the Brumbies have only one.
Queensland Reds (54) of Australia are also certain to feature in the knock-out stage and record seven-time champions Canterbury Crusaders (51) of New Zealand need two points to be sure of joining them.
While the fixture-less Reds looked on, All Blacks playmaker Dan Carter gave a masterly display for the Crusaders in a 40-12 away triumph over Otago Highlanders, who continue to prop up the standings.
Assuming the Crusaders do not slip up — they finish with two home games — there will be one place up for grabs and it should rest between Central Cheetahs (46) of South Africa and Auckland Blues (44) of New Zealand.
The teams clash at the Free State Stadium in Bloemfontein, South Africa, on Saturday in a match-up likely to reward the winners with a top-six finish.
Both lost this weekend, with a late try condemning Blues to a 22-20 defeat against Sharks, while Cheetahs went down 28-3 against Western Stormers.
Hurricanes restricted Chiefs to a 17-15 halftime lead in Hamilton, but the title-holders took control after the break and replacement prop Ben Tameifuna snatched the bonus-point fourth try.
At the lower end of the standings, debutants Kings from Port Elizabeth are doomed to finish last in the South African conference, meaning a two-leg play-off with the Johannesburg-based Golden Lions for a Super 15 place for next year.
Crusaders host Chiefs on Friday in the penultimate round, followed by Hurricanes-Highlanders, Cheetahs-Blues, Kings-Stormers and Bulls-Sharks showdowns a day later.