Tamsyn Lewis may make late call on 400m

World indoor champion Tamsyn Lewis could delay a decision on whether to run the 400m at the Olympics until as late as 24 hours before the heats.

Lewis has qualified for the 400m and her favoured 800m in Beijing, but faces the daunting prospect of racing on five successive days if she made the finals of both at the Games.

Of most concern are the 400m heats and 800m semi-finals being held on the same day, which could impact heavily on the Australian's 800m hopes.

The 29-year-old has rocketed into medal contention for the 800m after upsetting a top-notch field at the world indoor championships in Spain last month.

Lewis said she would leave the decision up to her coach and brother Justin Lewis.

He is likely to make the call for the 29-year-old as late as after the 800m heats on day one of the track and field competition on August 15.

But Lewis was upbeat about competing in both events despite the logistic nightmare it appears on paper and the widely publicised concerns about the humidity and air quality waiting in Beijing.

"I can do both if I have to do both. I train harder than I race," Lewis said.

"It depends also on the conditions. If it is as bad as everyone says, it might be far more difficult to do both than in a climate like Australia's.

"I'll just do whatever my coach says. The good thing about having a really good coach is you don't have to think, you just do whatever he says."

Lewis said she was more concerned with the likely humidity in Beijing rather than the dubious air quality.

She will shoehorn a training stint in Darwin in between the European athletics season which starts in four weeks, and the Australian pre-Games training camp in Hong Kong.

Lewis will also only enter the Hong Kong camp for five days before heading to Beijing three days before the 800m heats.

"I'm going into Beijing really late. I'm going to go in on the 12th (of August), and my race is on the 15th," Lewis said.

"The main reason of going to Darwin is because I want to train with my brother, it's humid up there, and it seems the logical place to base myself for two weeks to acclimatise."