London, Aug 5 (IANS/CMC): Defending champion Usain Bolt and nemesis Yohan Blake easily won their first round heats to qualify for the semi-finals of the men's 100 metres at the London Olympics here Saturday.

Bolt, the star in Beijing four years ago and Blake, the reigning World champion, were joined by fellow Jamaican Asafa Powell in winners' row while Trinidad & Tobago's Richard Thompson, the silver medal winner in Beijing, and his teammate Keston Bledman, were among those also qualifying for Sunday's semi-final.

Both Bolt and Blake are heavy favourites to win the final, slated for later Sunday night.

Bolt, who stumbled at the start, recovered easily to take heat four in 10.09 seconds with Antiguan and training partner Daniel Bailey following him across the line in
10.12 seconds.

The 25-year-old, seeking an unprecedented second straight sprint double, was careful not to extend himself and nonchalantly jogged the event.

"We have come to the conclusion that I shouldn't worry about my start," Bolt said after his first run in the United Kingdom capital.

"I'm working on the last 50 metres which is my strong point so that my focus right
now."

Blake, however, recorded the day's fastest time among Caribbean competitors, as he clocked 10 seconds flat to win heat six ahead of ahead of Japan's Ryota Yamagata (10.07).

Antoine Adams of St. Kitts and Nevis also made it through as one of the fastest losers from this heat with 11.22, but there was no such fortune for Jeremy Basscom of Guyana who failed to make the cut with 10.31.

Powell, too, made light work of heat five, running hard for only the first 70 metres before also shutting down to cross the line in 10.04 seconds.

He left the blocks quickly and took with him World junior champion Adam Gemili of Great Britain who was second in 10.11.

"I think I executed a pretty good race. If you watch the slow motion you can see where the blocks move, so it kind of threw me off," Powell said afterward.

Barbadian Ramon Gittens finished sixth in 10.35 and Paul Williams of Grenada seventh in 10.65, to miss out on the next round.

The Americans, however, were more dominant as they sent a stern warning ahead of
Sunday's penultimate round.

Ryan Bailey blazed to a fast 9.88 to equal his personal best in heat three, where Cayman Islands' Kemar Hyman clocked 10.16 to be fourth and make the semi-finals as one of the fastest losers.

Bailey's time eclipsed the 9.97 clocked by his teammate Justin Gatlin in winning heat two ahead of Bahamian Derrick Atkins (10.22) and Trinidad & Tobago's Rondel Sorrillo (10.23), both of whom qualified for the semi-finals.

Tyson Gay opened first round action with a win in 10.08, ahead of Thompson in 10.14. Bledman, meanwhile, qualified from heat seven after finishing third in 10.13 behind
winner Dwain Chambers of Great Britain (10.02).

Bahamian Warren Fraser missed out when he finished fourth in 10.27.

In the first semi-final Sunday, Powell and Bledman will clash with Gatlin while in the second semi should be hotly contested with Bolt, Daniel and Ryan Bailey, along with Thompson all going head to head.

Blake will meet Gay in the third semi-final, with Atkins, Sorrillo and Hyman also involved.