Rio 2016: Katherine Grainger at risk of missing Rio Games
Olympic champion Katherine Grainger is in danger of missing out on a fifth Games in Rio after her partnership with Vicky Thornley was dissolved.
The 40-year-old won gold in London with Anna Watkins after three consecutive silvers and was expected to be selected in the double scull again this summer.
But the Scot and Wales' Thornley, 28, have struggled since winning European bronze last year.
"It has put my Olympic place in the balance," Grainger said.
Speaking to The Sunday Times, she added: "I've never been in this position before, not having a seat in a boat so close to an Olympics. But I don't want to walk away from it now."
Grainger - Britain's most decorated female Olympian alongside swimmer Rebecca Adlington - returned in September 2014 following a two-year sabbatical in the aftermath of the London Games.
In the absence of the retired Watkins, Grainger was paired with Thornley and the duo finished sixth at the World Championships last September to qualify the boat for Rio.
However, their failure to make the podium at this year's European Championship earlier in May precipitated the end of their partnership, with the news broken to the pair on Friday.
British Rowing confirmed that both Grainger and Thornley will "be given the opportunity to be considered" for a place in the eight, but face a tough task after the current crew earned European gold in Brandenburg.
"The double has been very close to my heart so I'm very sad about the decision," Grainger added. "Defending the title was a driving factor in me coming back.
"If we can help to make the eight faster, it's a very exciting opportunity. But it has been made clear to us that we will have to earn our places."
|Grainger's roll of honour|
|Olympic gold: London 2012 (double sculls)|
|Olympic silver: Sydney 2000 (quad sculls), Athens 2004 (coxless pair), Beijing 2008 (quad sculls)|
|World champion: double sculls 2010 & 2011; quad sculls 2005, 2006 & 2007; coxless pair 2003|