WINDSOR (England), July 30: Australia threw down the challenge to archrival Britain in the men’s four at the Olympic rowing regatta on Monday, setting one of two Olympic-best times on a sunny final day of heat racing.

The flagship boats of both countries made their first appearances on Dorney Lake, with Australia making a bigger impression by winning the first heat in 5 minutes 47.06 seconds behind a slight tailwind. That broke Germany’s Olympic-best time from eight years ago in Athens by 1.46 seconds and they seemed in no way exerted in easily beating Germany and Canada, who also qualified.

Britain, who have won this event at the last three games and are also the world champions, clocked 5:50.27 to win the second heat in fairly nonchalant fashion under sunny skies. But they are no longer the dominant force in the event after a rapid Australian improvement over the past year.

The United States won the third heat in 5:54.58 and could also be a contender for gold. The US have strengthened their four for the London Olympics and are something of an unknown quantity.

The men’s four will also be the final race of the eight-day meet.

Earlier, Katherine Grainger’s quest for an elusive Olympic gold got off to the perfect start when she broke the Olympic best in the women’s double sculls with British partner Anna Watkins in the first heat.

They smashed the previous best held for 20 years by Germany by nearly five seconds, crossing the line in 6 minutes, 44.33 seconds.New Zealand, the defending champions, came second to also qualify to Friday’s final. Australia and Poland advanced from the second heat, with the Aussies also going under the previous Olympic best time by 0.20 seconds.—AP