Usain Bolt, unsurprisingly, looked a little tired on Tuesday as he began his bid to add the 200 meters world title to the 100 he secured so spectacularly on Sunday, doing the bare minimum to ease into the second round.

Bolt, the world record-holder at both distances having improved his 100 mark to 9.58 two days ago, made a sleeping gesture when his name was announced and duly looked stiff on the opening bend before lengthening his stride to come home safely in 20.70 seconds.

With 2007 champion Tyson Gay out because of a groin injury, Bolt looks an unbackable favorite for Thursday's final when the only question should be whether he can beat his own world mark of 19.30, set in Beijing last year.

To do so he will need better conditions than Tuesday's cool, blustery weather but after Sunday's astonishing display, nothing can be ruled out.

Beijing 200m silver medalist Shawn Crawford clocked the best overall time of 20.60 and should vie with fellow American Wallace Spearmon for silver.

The second round takes place later on Tuesday with the semi-finals on Wednesday.

In the 400 meters, Olympic champion LaShawn Merritt and world champion Jeremy Wariner stayed on course for their expected showdown in Thursday's final by qualifying comfortably through the opening heats.

High jump world champion Blanka Vlasic, a surprise loser in Beijing where she had been a hot favorite, also went through untroubled to Thursday's final.

Germany's Ariane Friedrich, the 2009 world leader with 2.06 meters and another with a point to prove after her own Olympic disappointment, needed only one jump to join her.

World and Olympic champion Gerd Kanter wasted little time in qualifying for Wednesday's discus final when he comfortably threw his opening attempt 66.73 meters.

Double world and Olympic champion Virgilijus Alekna, Beijing silver medalist Piotr Malachowski and Berlin-based Robert Harting, a real local hero who won silver in Osaka as a 22-year-old, also went through safely.

In daily life I've tried not to use my throwing arm too much in the last two weeks. I haven't seen my girlfriend so there was nothing to touch, said Harting.

All the favorites avoided trouble in some jostling in the women's 1,500 meters heats. The semi-finals are on Friday with the final on Sunday, the last day of competition.

There are five medals available in the evening session - the men's 400m hurdles, steeplechase and triple jump and the women's 400m and javelin.

(Editing by Justin Palmer)