Pete Reed and Andy Triggs-Hodge are set to defend their Olympic title in the men's four after being named in a new-look crew ahead of the forthcoming World Cup series.
Reed and Triggs-Hodge have spent the last three years racing in the pair but they have returned to Britain's flagship boat alongside Alex Gregory.
The final seat will go to either Tom James, who won gold alongside Triggs-Hodge and Reed in 2008, or Alex Partridge once they have finished testing.
Ric Egington and Matthew Langridge have moved from the four, who were world champions in 2011, to a strengthened eight that will be stroked by 20-year-old Constantine Louloudis.
Greg Searle is also in the eight and now on the verge of completing a remarkable Olympic comeback, 20 years after winning gold at the 1992 Games in Barcelona.
Although this squad is for the first of three World Cup regattas, in Belgrade at the start of May, GB Rowing performance director David Tanner confirmed it will be the basis for Olympic selection.
"This is a very big day for the GB Rowing team," Tanner said. "It's the start of the most important season any of the teams have experienced."
He added: "I have absolutely no doubt that what we are showing will be the best team in depth and stand that Britain has put out on the water.
"Inevitably there will be some tweaks but what you see today will be the basis of our Olympic team."
Britain have changed 10 of the 14 Olympic class crews from last year's world championships.