Team GB's Helen Glover "has a fight on her hands" to win her third rowing gold medal after a disappointing display in the heats at the Tokyo Olympics.
The mother-of-three finished third alongside partner Polly Swann in the women's pairs, which was enough to advance to Tuesday's semi-finals but with a slow time compared to their rivals.
Glover is aiming to complete a remarkable comeback as she becomes the first British mother to compete in an Olympics in rowing, 14 months after giving birth to twins.
The defeat was her first for more than a decade, which has spanned 51 races and included Olympic golds in 2012 and 2016.
Olympic rowing gold medallist Dame Katherine Grainger told BBC One: "We haven't seen Helen back in the boat for five years.
"We all have - and continue to have - high hopes but... we also haven't seen the rest of the world for almost two years.
"So, Helen and Polly came back to do the Europeans and they won it, which was impressive.
"The big risks, the leading nations while Helen has been away have been the USA, Canada, New Zealand and Australia - they were all to come back in and what they have shown here at the global level is just how good they are.
"They have a fight on their hands but this is the Olympics, they won't give the title up easily."
Glover admitted it was not an ideal start and also added that it was her son Logan's third birthday: "There's so much more important things going on than just racing a heat out here in Tokyo. There's my little boy at home. We'll celebrate when I get back.
"It wasn't our perfect row but I guess there's value in learning in the early rounds. We're open to what's going to come next."
Elsewhere, the men's four - Ollie Cook, Matt Rossiter, Rory Gibbs and Sholto Carnegie - are bidding for the GB boat's sixth consecutive Olympic gold medal and eased to victory in their heat to progress straight to the final.
Emily Craig and Imogen Grant are into the semi-finals of the lightweight double sculls, finishing second in their heat behind Romania.
The women's four - Rowan McKellar, Harriet Taylor, Karen Bennett and Rebecca Shorten - were fourth in their heat and must fight through the repechage to stand a chance of reaching the final, as must the men's eight, featuring GB flagbearer Moe Sbihi, who placed third in their heat.