BEIJING (AFP) - World record holder Usain Bolt scorched into the men's 100m final of the Beijing Olympics here on Saturday, posting the second fastest time in Games history in his semi-final. But reigning double world champion Tyson Gay of the United States crashed out, finishing only fifth in 10.05sec in the second semi-final which was won convincingly by Bolt's Jamaican compatriot Asafa Powell in 9.91sec. Bolt eased up after 65 metres to win his semi with effortless ease in 9.85sec, a time beaten only in Olympic standards by Canadian Donovan Bailey's gold medal-winning run at the 1996 Atlanta Games. The US team will be represented in the final later Saturday by Walter Dix and Darvis Patton, while there will be six Caribbean sprinters. Bolt and Powell will be joined by countryman Michael Frater, the Trinidadian duo of Richard Thompson and Marc Burns, and Churandy Martina of the Dutch Antilles. The semi-finals of the women's 800m saw fancied Kenyan duo Janeth Jepkosgei and Pamela Jelimo cruise through to Monday's final. Mozambique veteran Maria Mutola also produced a last-gasp home-stretch sprint to qualify for her fifth Olympic final. Earlier on Saturday, walker Valeriy Borchin held off former champion Jefferson Perez of Ecuador to hand Russia its first athletics gold of the Beijing Olympics. Borchin won the men's 20 kilometres race walk in one hour, 19 minutes and 01 seconds for Russia's first-ever Olympic walking success. The 22-year-old, who served a one-year drugs ban in the 2005/06 season, beat home 1996 Olympic champion Perez by 14 seconds, with Australian Jared Tallent a further 27 seconds adrift in the bronze medal position. "I never expected to win this medal," said Borchin, who opened up the decisive gap over Perez with two kilometres to go. "At the beginning, I was lagging behind. I feel my dream has come true."