WORLD singles record holder Zac Purchase proved unstoppable at the 5km British rowing trials in Boston, racing home 13 seconds clear of the field in the lightweight time-trial.

Evesham Rowing Club's Alex Gregory was also on form to finish second in the men's heavyweight race.

King's School Worcester product Purchase earned bragging rights over his GB world medal doubles partner Mark Hunter, beating him into third by 15 seconds in the 54-boat race-off against the clock.

The 2006 world 72kg singles champion said: "It's a good confidence boost because I wasn't going that well in the single the week before.

"It shows I've got the strength and fitness to still come home in front and, at this stage with eight months to the Olympics, that's good to know."

Going off at the head of the field in the 72kg class, Purchase had Hunter in his sights right behind him and steadily moved away over the whole of the course to finish in 17 minutes 32 seconds.

Worcester Rowing Club's Matt Beechey, who took World Cup gold, silver and bronze with Dan Harte in the GB 72kg pair this year, was 10th in 18.14.

Purchase and Hunter have just returned from a 10-day camp in Seville, where they rowed together in their double scull for the first time since landing world bronze and qualifying for the Olympics in Munich last September.

"It went really well, in fact better technically than throughout our first season together," added the 22-year-old, who broke the world 2,000m lightweight singles record, taking world gold on the London 2012 Olympic rowing lake last year.

"It's obvious that we've still got a lot of potential to go even faster in the double and that's a great boost for Beijing.

"Looking back at 2007, we came together in April and although we were quick, we never quite nailed it technically.

"There was plenty we were doing wrong but, having worked in singles and then come back together, we're now putting those things right."

Hunter has beaten Purchase in training and also in the British indoor rowing championships last month but the Worcester man said: "I don't think he'll be that happy with his result this time."

The duo are set to return to Seville for another 17 days in January after they get well-earned days off on Christmas Day and New Year's Day.

"We're well into the really hard winter programme at the moment and it's good to know my strength levels are improving," added Purchase, who moved into the double this year because the singles is not raced at the Olympics.

"It's not long to the Games but I'm not really thinking about racing there yet. The training is tough and it's day-to-day focus for now.

"We've just got to work on getting fitter, tougher and moving the boat more efficiently. No doubt, when we get to the World Cup season in May, the excitement level will start to build but for now it's all about doing the hard yards."

Wormington's Gregory held off the challenge of his GB quadruple scull crew-mate Simon Fieldhouse by just 0.27 seconds to finish second in the heavyweight race, crossing the line in 20 minutes dead.

It was a good confidence boost for 23-year-old Gregory, who also had Sydney 2000 Olympic eights gold medallist Kieran West 25 seconds behind him in ninth.

Malvern world under 23s medallist Colin Scott was 17th in 19.26 in the 34-boat men's pair race with Cambridge partner David Billings, just four days after racing the Light Blues eights trial.

Worcester world junior singles finalist Sarah Cowburn and the city's British singles champion Jo Lyons pulled out on medical grounds from the women's race but hope to get another chance at the next trials in February.