Rio Olympics 2016: Helen Glover and Heather Stanning into semi-finals

Britain's defending Olympic champions Helen Glover and Heather Stanning reached the semi-finals of the women's pair in Rio with victory in their heat.

Glover, 30, and Stanning, 31, trailed Denmark with 500m to go but finished strongly to extend their unbeaten run, which stretches back to 2011.

The men's four produced a dominant display to comfortably win their heat.

Great Britain's men's and women's eights and the men's quadruple sculls team reached their respective finals.

"We won," said Stanning after a hard-fought heat. "We did what we needed to do and we are into the semi-final.

"It is all about the final at the end of the day and we have to make sure we get there in good shape."

The women's eight were third at halfway but overhauled New Zealand and Canada while the men's quad were second behind Germany in their repechage to progress.

Pete Reed, a two-time Olympic champion in the men's four and now part of the eight, said: "It'll be a street fight. The desire is still there, it's burning inside."

Polly Swann, part of the women's eight, said: "We weren't worried that we were a bit behind, we just held our heads and I'm so proud of the way we've come out here with a bang and set ourselves up for the final."

The men's quad knew anything other than a top-two finish would see them eliminated, and Angus Groom, Peter Lambert, Jack Beaumont and Sam Townsend responded to reach Wednesday's final.

Elsewhere, Britain's John Collins and Jonathan Walton reached the semi-finals of the men's double sculls by winning the repechage.

And compatriots Richard Chambers and Will Fletcher progressed to the semi-finals in the men's lightweight double sculls by finishing second in their heat.

But defending champion Katherine Copeland, now rowing with Charlotte Taylor, failed to qualify from their women's lightweight double sculls heat.

The pair have a second chance in the repechage on Tuesday.

Analysis - James Cracknell, double Olympic champion

On the women's lightweight double sculls: "If you are not on your game at the Olympics, you are going to be in trouble. It's harsh but the truth. If they haven't been able to put changes into place on the training ground over two months they can't do it before the repechage."

On the men's four: "That was a scary and impressive display. They've laid down a marker now to the rest of the field and overall it's been an excellent day for men's heavyweight rowing."

On the women's pair: "This will be a wake-up call for them. They were taking more strokes than Denmark to maintain the same speed so that is certainly something to work on before the semi-final."

On the men's eight: "Their win was the textbook way to row a heat - lead from the start, dominate through the middle and just watch as the other teams battle it out."

On the women's eight: "They responded incredibly well. This is going to give them a huge amount of confidence. They kept themselves very cool. At one stage it looked like Canada could have been racing New Zealand but to win the race after being down shows they have the resilience."

• Day-by-day guide to what's on

• Latest medal table

Subscribe to the BBC Sport newsletter to get our pick of news, features and video sent to your inbox.