Veteran Katharine Grainger is to go it alone in a single scull as she begins her quest for gold at London 2012.
The 33-year-old Scot, who has won three successive Olympic silver medals, will race in the single for the World Cup regatta near Barcelona on 29-31 May.
Andy Hodge and Pete Reed, Beijing Olympic gold medallists in a four, will compete together in a pair.
And Zac Purchase - whose doubles partner Mark Hunter is taking a year off - will race the lightweight single.
Purchase is recovering from an illness and will have another fitness test before the season-opener but hopes to be in the Olympic-class double scull later in the year.
I thought I would give it a go, although I don't know how long it will be for - I don't have to make a firm commitment
Katharine Grainger
GB Rowing rarely make major changes to their top line-ups during the course of a season so most of these crews are likely to compete at the World Championships in Poland in August.
Six of the top eight rowers at the Beijing Olympics - in the men's four and women's quadruple scull - competed in those crews at the first World Cup event of 2005 and this squad could be similarly significant for London 2012.
Grainger returned to training in January determined to go a step further after taking silver in a quadruple scull in Sydney and Beijing, and a pair in Athens.
She was seven seconds ahead of her nearest rival, Anna Bebington, in the national trials earlier this month.
Grainger told BBC Sport: "One of the things I really enjoy is the team element and the thought of going in to the next race with no-one to prepare with is quite tough.
"I thought I would give it a go, although I don't know how long it will be for - I don't have to make a firm commitment."
Two of her crew-mates in the Beijing quad, Frances Houghton and Debbie Flood, have taken a year off to mull whether they will continue until 2012.
The fourth member of that crew, Annabel Vernon, will rejoin her former partner Bebington in the double scull.
Of the men's four who won gold in Beijing, Tom James and Steve Williams are not in action this year, with James taking a year off and Williams yet to decide on his future.
So Hodge and Reed are reforming the pair that won four successive national trials between 2005 and '08.
"There's lots to improve on and a lot more riding on us," said Hodge.
"There's a bit more pressure but there's no reason why we can't go well."
Three of the silver-medal-winning eight - Alex Partridge, Richard Egington and Matthew Langridge - will join top prospect Alex Gregory in the four.
The only unchanged crew from the Beijing Olympics is the bronze-medal winning double scull partnership of Matthew Wells and Stephen Rowbotham.
Hunter, who took gold with Purchase in the lightweight double scull, has taken a year off to coach in the USA but is expected back next season.
Purchase will revert to the lightweight single, a non-Olympic event where he broke the world record on the way to becoming world champion in 2006.
A new lightweight double will feature Paul Mattick, 2007 world champion in the lightweight men's four, and 2008 Olympic reserve Rob Williams.
But looking ahead to the World Championships, Purchase said: "I think I want to be in the double.
"The challenge of winning the World Championships the year after winning the Olympics is something I don't think has ever been achieved.
"That's a challenge I'm quite happy to grab with both hands and shake until it's ours."
More crews, likely to include a women's quad and men's and women's eights made up of development rowers, will be announced in mid-May.
GB Rowing performance director David Tanner said: "We have an interesting season ahead.
"It will be one of rebuilding, one in which we will try new things, giving the chance for our best Olympians to find new challenges and for newcomers to make their mark at the start of the new Olympiad."
GB squad for opening World Cup regatta on 29-31 May
Women
Single scull: Katherine Grainger
Pair: Olivia Whitlam, Louisa Reeve
Double scull: Annabel Vernon, Anna Bebington
Men
Single scull: Alan Campbell
Double scull: Matt Wells, Stephen Rowbotham
Pair: Peter Reed, Andy Triggs Hodge
Four: Matt Langridge, Richard Egington, Alex Gregory, Alex Partridge
Lightweight women
Double scull: Hester Goodsell, Sophie Hosking
Lightweight men
Single scull: Zac Purchase
Double scull: Rob Williams, Paul Mattick
These crews will be formally confirmed, and more crews added, in mid-May.
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