"I don't envy these guys running out there in this heat," Umaga said. "It's amazing what they put themselves through."
Umaga's men, alongside the fellow unblemished Chiefs and Crusaders, were most impressive on day one.
First up the Blues trounced local favourites the Reds 29-7 and then monstered Robbie Deans' Panasonic Wild Knights 47-10, the biggest win in the tournament's tenure.
Carlos Spencer made his comeback, knocking over a couple of easy conversions but didn't attempt any trick plays with his team-mates turning it on.
"I've been looking forward to this for a long time. I've been away for 13, 14 years so being back is a privilege for me. I was very excited to get out there with these young guys," Spencer said. "I reckon this game would've suited me back in the day. It's got the combo between sevens and XVs.
"There's loads of talent in this team and it's a good way to build towards Super Rugby. To get wins over the Reds and Wild Knights and put that sort of a score on them is good."
On one occasion Spencer loomed up inside Caleb Clarke but the teenage talent opted to back his pace.
"I can imagine Eroni Clarke sitting up there saying 'you better give it' and he didn't so he might get a clip around the ears from the old man," Spencer laughed.
"I'm just happy to get through the game. I took bugger all contact, if any, and hopefully it goes that way if I get another opportunity."
Melani Nanai and Sam Nock were influential but it was collectively aggressive defence and support play that set the tone for the Blues.
Expectations must be tempered somewhat, as the Blues are in the easiest pool and yet to face Kiwi opposition, but confidence appears to be growing in this format.
Should Tim Nanai-Williams continue his magic touches, the defending champion Chiefs will be well in contention, too. Nanai-Williams' quick feet proved impossible to contain while Taleni Seu and Te Toiroa Tahuriorangi also had their moments as the Chiefs snuck past the Highlanders, thanks to a last play call.
Colin Cooper's side also thrashed French club Pau, who despite carrying seven former All Blacks look out of their depth and comfort zone after arriving from snow.
The Crusaders, last year's beaten finalists here, cruised past the Hurricanes 22-0 in their opening derby with a statement of intent, and were superb in blowing away the Brumbies 31-7 in the final match.
With firepower in the form of Jone Macilai and George Bridge complementing rolling maul tries, the Crusaders appear the team to beat.
Fielding a young, inexperienced team led by Julian Savea, the Hurricanes consistently made errors and never fired a shot against the Crusaders. It was a disjointed, bumbling effort. While improved, their 12-5 win over Fiji was largely unconvincing, suggesting they are the worst New Zealand side at this tournament.
The Highlanders, and their high-vis jerseys resembling road workers, bounced back from the opening defeat with a late try to defeat the Waratahs. Canterbury wing Josh McKay and Tevita Nabura were dangerous for the southerners throughout.
Of the others, the Waratahs and Henry Speight's Brumbies, who took down Fiji in a tight tussle, are the best of the Australian teams. Neither is likely to contest the final, though.
While the crowd built as the day progressed, organisers will be hopeful much more than day one's 11,430 turn up for the finals.
With the only two New Zealand defeats coming against their counterparts, Kiwi punters can at least look forward to more success.
Day one results:
Pool A
Wild Knights 19 Rebels 17
Blues 29 Reds 7
Blues 47 Wild Knights 10
Rebels 21 Reds 17
Pool B
Waratahs 31 Pau 10
Chiefs 17 Highlanders 12
Chiefs 31 Pau 7
Highlanders 12 Waratahs 10
Pool C
Brumbies 17 Fiji 12
Crusaders 22 Hurricanes 0
Hurricanes 12 Fiji 5
Crusaders 31 Brumbies 7
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