The Hurricanes held off a Western Force fightback to make it three wins out of four this season with a 31-23 win in Napier on Friday night but the Brumbies became the latest former champions to be humbled in Fiji after a 42-27 loss to the Drua.
The Blues needed a bonus-point win to join them at the top and already had a try from Sam Nock on the board when the scrumhalf's opposite number Augustine Pulu was shown a yellow card, later upgraded to red, for a high tackle on him in the 16th minute.
Although shorthanded, Auckland-based Moana battled hard to cross through hooker Mills Sanerivi and had a couple of scores chalked off for infractions, but the Blues scored tries through centre AJ Lam and prop Ofa Tu'ungafasi to lead 15-7 at the break.
Converted tries from prop Marcel Renata and lock Sam Darry took the lead out to 29-7 after 50 minutes before pacey winger Cody Vai and replacement prop Mason Tupaea added two more to hand Moana a fourth straight heavy defeat.
"I think the scoreboard doesn't reflect how physical that game was," said Blues skipper Dalton Papali'i.
"Moana, they're strong, powerful athletes and you know it's always going to be a grudge match. The boys are going to be pretty sore."
The fourth-placed Waikato Chiefs had a bye and were joined on 13 points by the Queensland Reds, who scored two tries in the last 10 minutes to beat the NSW Waratahs 26-17 at Brisbane's Lang Park on Saturday.
Wallabies flyhalf Carter Gordon, whose last-gasp try got the Reds past the Brumbies in round four, showed a good turn of pace to grab his second try of the match with a mazy run from halfway, sealing the victory a minute from time.
The Canterbury Crusaders earlier overturned a 15-12 halftime deficit to down the Otago Highlanders 29-18 in New Zealand's south island derby and record their second win of the season.
Debutant openside flanker Johnny Lee scored twice off attacking lineouts in six minutes in the third quarter to put the reigning champions ahead and the Highlanders were held scoreless for the remainder of the contest.
The Crusaders joined the Highlanders on nine points, one behind the sixth-placed Waratahs and one ahead of the Drua, who on Saturday made the most of the steamy and wet conditions in the first Super Rugby match played in the town of Ba.
The Brumbies, who made 10 changes to the team edged by the Reds in round four, were in touch at 20-12 down at halftime but wilted after the break as fullback Iliasia Droasese touched down twice and hooker Sairusi Ravudi also scored a try on debut.
The Hurricanes also trailed at halftime in a physical battle in Napier but four tries in the second half gave them enough of a cushion to seal the deal when the Force stormed back with two five-pointers in the last 10 minutes.
