While they both won, things were a little tougher for double sculls combinations Eve Macfarlane and Zoe Stevenson and Chris Harris and Robbie Manson, with the men just edging out Azerbaijan on the line.
The men's lightweight four of James Lassche, Peter Taylor, Alistair Bond and James Hunter underlined their medal credentials with a sound win, in the fourth-fastest time.
The quad's struggles came as no surprise, having qualified belatedly after a Russian crew were ruled out five weeks ago following a doping violation.
Jade Uru, Nathan Flannery, George Bridgewater and John Storey were 7sec behind heat winners Estonia and ninth-quickest out of 10 crews.
The New Zealand women's sevens team meanwhile showed off their class by smashing Kenya 52-0 at the Deodoro Stadium as the Olympics welcomed rugby sevens into the fold.
It took only 13 seconds for star flyer Portia Woodman to cross for the first try and it was all one-way traffic from there as the gold medal challengers overpowered and overwhelmed the Kenyans.
Kayla McAlister scored two minutes later and Woodman could have had a second soon after but she inexplicably dropped the ball as she sped to the line.
The New Zealanders took a 21-0 lead into the break and the second started like the first when Woodman scored again from the kickoff.
The dangerous speedster finished with a hat-trick while McAlister crossed for a double in the eight-try rout. The New Zealand team face Spain next up this morning.
On the hockey turf, a second-half fightback gave the Black Sticks a glimmer of hope, but gritty defence laid the base for Australia's 2-1 win in their opening men's hockey match at the Rio Olympics.
The world No.1 Australians went into the break with a two-goal lead through Chris Ciriello and Matt Gohdes, but the Kiwis hit back barely 60 seconds after the restart when James Coughlan found the net.
New Zealand thought they'd found an equaliser when Hugo Inglis deflected in a vicious cross from Hayden Phillips only for the video referee to rule it out.
It was a largely forgettable opening day for New Zealand's swimmers, with only breaststroke specialist Glenn Snyders advancing out of his heat.
It initially looked as if Snyders would have to swim-off for a place in the semifinals after recording the 16th equal fastest time with Hungary's Daniel Gyurta. But the Hungarian opted not to take part in the swim-off, allowing Snyders to take the last remaining spot in the semis.
Britain's Adam Peaty was fastest qualifier, posting a sizzling world record time of 57.55 in the heats.
Helena Gasson finished last in her heat of the 100m butterfly, with her time of 59.82 about 0.3 of a second off her personal best.
Matt Hutchins was more competitive in the 400m freestyle, finishing second in his heat.
But his time of 3:48.25 - a PB - placed him 19th overall, just off the semifinal pace.
