Green: Bolt from another planet

Former world champion Maurice Greene believes Usain Bolt remains in a world of his own.

The Jamaican begins his attempt to add World Championship glory to his three Olympic gold medals.

Greene won the world title three times in succession (1997, 1999 and 2001) and believes Bolt will relieve defending champion Tyson Gay of his 100 and 200 metres titles in Berlin.

"Usain is running on Mars, everyone else is still running on Earth," insisted Greene, who dominated the sport on his way to world titles in Athens, Seville and Edmonton.

"I would tell Tyson Gay to try to block everything else out. The only person in the race is you. That's how you have to go into it.

"In the 2000 Olympics I told my manager it was my gold medal to lose and that's how Tyson has to approach it. That's how his mindset has to be. He has to believe."

The first two rounds of the 100m take place today with the semi-final and final scheduled for Sunday in an explosive start to the championships.

Other highlights of day one include the heptathlon and heats of the women's 400 metres, with Britain's Jessica Ennis and Christine Ohuruogu looking to stamp their authority on their respective events.

Ennis set a new personal best and world-leading score of 6,587 points on her comeback from injury in May and will expect to win the 100m hurdles, the first of the seven disciplines.

The 23-year-old from Sheffield - who is even hoping to contest the individual 100m hurdles event which starts on Tuesday - should also do well in the high jump on the opening morning, with the shot and 200m to come in the evening session.

Ohuruogu has struggled for form this season and also saw her preparations for Berlin disrupted by a recent hamstring injury, but the defending champion and Olympic gold medallist has a formidable record in major championships.

The Londoner has never lost a major championship final and will be hoping main rival Sanya Richards has burnt herself out on the European Grand Prix circuit, where the American has run under 50 seconds five times this season.

Richards famously built up a big lead in last year's Olympic final in Beijing only to pay for going off too fast and fade badly down the home straight as Ohuruogu came through to win.