World champion rower Mahe Drysdale feels New Zealand's Olympic gold medal chances could be jeopardised by a ding dong battle with Rob Waddell for the single sculls spot.

Waddell beat Drysdale by two boat lengths over the weekend in the first of several duels in the coming months.

While Drysdale says it is positive being pushed week to week, it could go pear shaped if they both have to peak in March at the Olympic trials.

But he says there is a lot of water to go under the bridge in the coming months.