Leading Irish medal hopefuls Paul O'Donovan and Fintan McCarthy powered to victory in their heat in the men's lightweight double sculls at the Sea Forest waterway in Tokyo.
The Skibbereen pair - reigning world and European champions in the event - took charge of Heat 2 just before the halfway point, gliding past the Uruguayan duo who had made the early running before fizzling out.
From there, a race victory was never in doubt, and they won comfortably from the Czech Republic, who beat the Polish duo to second place.
O'Donovan and McCarthy progress to the semi-final with a minimum of fuss, with Germany and Norway winning the other two heats in the event.
"We feel alright," said O'Donovan. "You'd be a bit tired after racing out there. It’s very warm, they have plenty of sunshine in Japan.
"But we’ve been preparing for that so it’s alright. Nice to get the first race out of the way and all that shebang."
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McCarthy revealed that the duo had prepared for the heat and humidity by doing "some cycling in our bathroom in Italy" with heaters and the shower on.
"Things are going well enough so far so we’ll just try to keep the momentum going and just try to do what we do, stick to our guns," he said.
As to being considered strong contenders in their event, O’Donovan said: "We’re only out there doing the rowing thing. We’re not doing it for other people, for them to have a thought about us, we’re here for ourselves, really.
"If people want to think we’re favourites or whatever, they can do that, we don’t care about that.
"I think go to bed to be honest, don’t mind watching us fools here, there are repeats on in the morning, I’m sure!"
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This win was quickly followed by another superb Irish effort in the women's four, with the quartet of Aifric Keogh, Eimear Lambe, Fiona Murtagh and Emily Hegarty easily qualifying for the final, finishing a close second behind the highly-rated Australians in their heat.
Starting in lane two, the Irish four set off early with the Australian boat, the pair ultimately putting huge distance between themselves and the remainder of the competition.
Romania wound up finishing a distant third, with USA and Denmark bringing up the rear. The Irish four took bronze at last year's European Championships and secured their place in Tokyo with a win in Lucerne in May, and are now bound for the final on Wednesday morning.
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Earlier in the day, Philip Doyle and Ronan Byrne progressed to the semi-final of the men's double sculls after surviving Saturday morning's repechage.
The Irish duo were plunged into the repechage after leaving it too late in Friday's heat, eventually finishing fourth.
Doyle and Byrne lined up against Germany, Czech Republic and Lithuania, with three of the four advancing to the semi-finals.
The Czechs led early with Ireland and Germany vying for second spot for the first half of the race, while the Lithuanians followed in their wake in fourth.
But while the Lithuanians - silver medalists in this event in Rio - surged in the second half of the race, the Czechs fizzled out, dropping to the rear of the field.
Doyle and Byrne finished in third spot behind Germany and Lithuania, enough to book their spot in the semi-finals.
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"Frustration" was the overriding emotion for Doyle, despite qualification.
"We're obviously here to do something more than what we're achieving," he said.
"But we’re happy that even on a bad day we have the base speed to make it through the rounds.
"At the moment, we’re just happy to be at the next level where we can try again, and we’re not out of it."
Aileen Crowley and Monika Dukarska missed out on automatic qualification to the women's pair semi-finals.
A top-three finish in Heat 3 would have qualified the Irish duo directly into the semi-finals.
After a solid start in which they were third ahead of their Spanish counterparts, Crowley and Dukarska slipped back to fourth in the final 500 metres.
They will compete in the repechage on Sunday for a second chance to seal a place in the semis.
Aoife Casey and Margaret Cremen are also into a Sunday morning repechage in the women's lightweight double sculls after a fifth place finish in Heat 1.
They finished in a time of 7:17.67, 14.20 seconds down on the leading French duo and outside the automatic qualification places for a spot in the semi-final.
