Katherine Grainger's reaction to winning silver at the World Championships could not have been more different to her tears at last summer's Olympic Games.

A third-consecutive Olympic silver medal had represented failure in Beijing and led to Grainger almost walking away from the sport.

Instead, the homicide PhD student opted for a new challenge and she chose to remain in the single scull after winning the national trials.

After a tough season and in a competitive field, it was widely expected that fourth place in Saturday's final would be the best she could expect.

Today, the medal was silver again - but this time it represented an extraordinary success for the 33-year-old from Glasgow

Grainger had made the podium just once during the World Cup series but she attacked the field today in a manner British rowing boss David Tanner described as "brave and brilliant".

The Belorussian Ekaterina Karsten powered through in the closing stages to claim her fourth straight world title, but Grainger greeted the result with a smile and hugs of joy.

"I wanted to learn as much as I could about myself this year. Coming to this regatta I didn't feel I was in a place where I'd be really competitive," said Grainger.

"I'm a perfectionist so I am thinking that maybe I should have won.

"It's a bit frustrating that I couldn't give it a big burn to the finish but I am over the moon with the result.

"You have got to love racing like that."

Moments after Grainger's success, Alan Campbell took the water in the men's event and produced the race of his life to win silver.

Campbell forced the dominant New Zealander Mahe Drysdale to smash the world record in order to claim a fourth title. The Ulsterman himself was a second inside the old mark.

"I was disappointed but I did the world's second best time and Mahe has blasted apart the world best time. It was a fabulous race," said Campbell.

Britain have seven crews in A finals action tomorrow.