Katherine Grainger makes her first appearance at the GB Rowing Trials this weekend since winning gold at London 2012.

The 39 year-old took two years out of the sport after the Olympic double scull triumph with Anna Watkins but recently announced she intends to make a bid for Rio.

The Trials - at Caversham - are a key stage in Grainger's bid to compete at a fifth successive Games, with performances influencing crew selection for this summer's World Championships, which double as Rio qualification.

In a tough women's single field, Grainger will face 2014 world top-eight sculler Vicky Thornley, twice Olympic silver-medallist Frances Houghton and British double scull champion Melanie Wilson.

Competing in the men's event is Grainger's fellow Glaswegian Angus Groom, who is looking to break into the senior ranks having competed at two Under-23 World Championships.

Munlochy's Alan Sinclair will be hoping to be among the front-runners when he partners Nathaniel Reilly O'Donnell in a men's pair field packed with World and Olympic champions.

Imogen Walsh of Inverness will continue her return to full fitness by competing against her tight-knit training group - including Olympic champion Kat Copeland, her double scull partner last year - in the lightweight women's singles.

Sam Scrimgeour of Kirriemuir - a bronze-medalist in the men's pair with Jono Clegg at the 2014 World Championships - goes in a high-quality lightweight men's field featuring Peter and Richard Chambers, Chris Bartley, Mark Aldred, Jamie Kirkwood and Will Fletcher.

European Champion Polly Swann, from Edinburgh, has been forced to sit out the Trials with injury.