The Reds thrashed Waratahs 46-14 to maintain their perfect start to the Super Rugby AU season and return to the top of the standings.

Substitute Alex Mafi's second-half hat-trick helped seal an emphatic victory for the leaders, who had not beaten the Waratahs in Sydney in eight years.

Will Harrison kicked three penalties for the hosts in the first half, but the Reds responded through tries from Tate McDermott, Lukhan Salakaia-Loto and Filipo Daugunu.

Taniela Tupou crossed over early in the second half to extend the Reds' lead and, while Will Harris touched down to give Waratahs a temporary reprieve, their opponents soon ran away with the game.

Mafi, brought on at the interval, scored the first of his three tries with a little over an hour played and added two more before full-time, either side of Hugh Sinclair and Zane Nonggorr being sin-binned for separate offences.

The Super Rugby Aotearoa clash between Chiefs and Blues earlier on Saturday was a lot tighter, with Damian McKenzie snatching a famous 15-12 win for the hosts in the final minute.

Akira Ioane found a way through 24 minutes in for the only score of the first half of what turned out to be a thrilling contest in Hamilton.

But the Chiefs, who had gone 11 matches without a Super Rugby win before beating Hurricanes last weekend, hit back through McKenzie's penalty and a Samisoni Taukei'aho try, the hooker grounding the ball in the midst of a maul of players.

That lead lasted just a few minutes, however, as Tom Robinson charged clear and dotted down for the Blues' second try, which Otere Black was unable to add to from the conversion.

And that would prove a costly miss as, with less than a minute to go, McKenzie rounded off a fine counter-attack and brushed himself down to add the extras for a memorable victory that lifts Chiefs up to third, now within two points of their opponents.