Grainger was distraught after being pushed into silver in Beijing
Olympic silver medallist Katherine Grainger put in a powerful display to win her eighth career title at the Great Britain rowing trials in Belgium.
Grainger won the women's single scull by an impressive seven seconds ahead of Anna Bebington and Annabel Vernon.
Alan Campbell sealed victory in the equivalent men's event but was pushed all the way by Olympic double scull bronze medallist, Matt Wells.
Olympic champion Peter Reed and Alex Gregory took the men's pair.
It was a fifth win in a row in the event for Reed while his usual partner and fellow Olympic champion Andy Triggs Hodge finished fourth in the men's single scull.
Reed and Gregory fought out a tense encounter with Olympic silver medallists Alex Partridge and Rick Egington, eventually triumphing by just over two seconds.
But Grainger's performance was one of the most impressive of the weekend.
The three-time Olympic medallist only returned to training in January after the disappointment of Beijing, but dominated her race in a field which included three other Olympic medallists.
The 33-year-old had edged ahead after 250 metres and by the 900m mark had built up a length lead.
Bebington, who won bronze in the double scull in Beijing, put in a strong performance over the last 350m to edge out Vernon, who won silver in the quadruple scull along with Grainger.
Sarah Winkless finished fourth with Beth Rodford fifth, although less than two seconds separated the second-to-fifth placed finishers.
"It's been a tough three months but I've worked really well with my coach, Paul Thompson, to get it right", said Grainger.
Campbell also set the pace in his race but Wells kept in contention in the third 500m and had enough left at the end to challenge Campbell to the line
"I'm pleased to win", said Campbell. "I always find the trials tougher than any World Cup. There is a lot of pressure.
"We've had so many people go under seven minutes and that's not happened in the past."
One of the day's more dramatic races came when Rob Williams came back from a length and a half down in the lightweight men's single scull final to pip 2007 lightweight men's four world champion, Paul Mattick, at the line.
Zac Purchase, Olympic gold medallist in the lightweight double sculls, was absent from the trails as he is recovering from illness, while his partner in Beijing, Mark Hunter, is taking a year off.
In the women's pair, Olympic finalists Olivia Whitlam and Louisa Reeve stamped their authority with victory by over four seconds from Alice Freeman and Jess Eddie.
Sophie Hosking won the lightweight women's single scull after a close race with Hester Goodsell and Andrea Dennis.