Bolt, the biggest name in athletics, returned to the Beijing track two days after pipping Gatlin to retain his world 100m title, and won his 200m heat in an easy 20.28 seconds. Gatlin topped his heat in 20.19.
Sweat dripping from his beard on a humid evening, Bolt then icily shrugged off the threat of two-time doping offender Gatlin in his favourite event.
"It actually means more to me than the 100m," said the world record holder, who recovered from pelvic trouble just in time to deliver positive headlines after allegations of widespread doping engulfed the sport.
Joining the heavyweights in the semi-finals was 16-year-old Japanese schoolboy Abdul Hakim Sani Brown, who clocked 20.35 behind Gatlin.
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"It's just a dream to be here," said Sani Brown, who was ordered by his Japanese mother to choose track over football when he was in elementary school. "I don't know if I can reach the finals but I think I can go faster," added the youngster, whose father is Ghanaian. "I'll give it everything."
"It's unbelievable," said Rutherford. "It's just the most incredible thing. I've been dreaming of this for a long time. I can't believe I've done this."
Australian Fabrice Lapierre took silver with 8.24m as home favourite Wang Jianan claimed bronze after leaping 8.18 to bring the house down in Beijing.