Usain Bolt began his bid to win the sprint double at London Olympics by cruising into the 200m semi-finals.The 25-year-old Jamaican was joined by countrymen Yohan Blake and Warren Weir, with France's Christophe Lemaitre and Britain's Christian Malcolm also through to the next round.Bolt, who successfully defended his 100m crown on Sunday, eased off to win his heat in 20.39 seconds.The 200m semi-finals are on Wednesday and the final takes place on Thursday.Four-time Olympic champion Bolt is also attempting to retain his 200m title from Beijing.After what was approaching a jog, he told BBC Sport: "The crowd is always wonderful, they play an important role in my running and I love my 200m."I try to do my part, I know what comes with winning, so all I have to do is try and enjoy it."Despite his vast experience, Malcolm, 33, said he was anxious about competing in front of such a huge home crowd."I don't like the early mornings but it's good to get the first one out the way," he said. "It is nerve-wracking to compete in this stadium, with so many people watching."The nerves are always there, it's because of the hunger and desire I have for the sport. I love athletics and will keep doing it until my body holds out."