WELLINGTON, March 5 (Xinhua) -- New Zealand's triple world champion Mahe Drysdale on Wednesday beat former Olympic gold medallist Rob Waddell in the third and final single sculls trial race on Lake Karapiro.

The result means Drysdale has won two of the three race series, which will help decide who will represent New Zealand in the single scull event at the Beijing Olympics.

Drysdale, 26, took control early in the race on Wednesday, finishing about 25 seconds ahead of Waddell.

Rob Waddell, 33, said a medical condition affected him on Wednesday, though he did not consider withdrawing from the race.

He said he has suffered an irregular heartbeat since the mid-1990s. He has been able to treat the condition until now but said an operation may be required.

Waddell announced a comeback to rowing last year after being a member of the Team New Zealand America's Cup defense team in 2003 and the challenger team in 2007.

The winner of the series will not automatically qualify for the Beijing Olympics because selectors also consider other factors when making their recommendation to Rowing New Zealand. The selectors' decision was due to be announced on Friday.

Waddell said without a doubt Drysdale should get the nod for the Olympic single sculls place.

There is hope that the loser of the duel could still go to the Beijing Games in August as part of another rowing combination.