Jamaica's former world record holder Asafa Powell was among the athletes left trailing while 2003 world champion Kim Collins of St Kitts and Nevis ran a personal best of 9.97 seconds at the age of 37 to finish fourth.
Free from the injuries which have hampered him since he won the 100 and 200 metres world titles in 2007, Gay has already produced season's best times in both events.
Gay, who raced in the U.S. trials less than two weeks ago, got off a good start before charging down the final 70 metres to destroy the field.
"It shows I'm fit and healthy and that's the key," Gay told Swiss television.
Asked by the BBC asked if he would face Olympic and world record holder Usain Bolt before the world championships, Gay replied: "Maybe, I'm not sure of my schedule."
Powell, who missed the Jamaica trials through injury, was happy with his performance after finishing second in 9.88, his best time of the season.
"I'm happy my times are getting better slowly but surely," he told the BBC. "I was really disappointed (about the Jamaican trials), I know how good I can be."
Injury-troubled David Oliver, who missed the London Olympics, won the men's 110 metres hurdles in 13.03.
"It feels good to be back, I'm running healthy," said the Beijing bronze medallist. "Lausanne is always a great event, it's a good stepping stone to Moscow."
Olympic champion Felix Sanchez was second in the 400 metres hurdles where he was beaten by Puerto Rico's Javier Culson, the bronze medallist in London, who produced a personal season's best of 48.14 seconds.
Ukrainian Mariya Reymyen produced an upset when she beat Kimberly Duncan and Carmelita Jeter to win the women's 200 metres in 22.61 seconds.
Her compatriot Bohdan Bondarenko leapt 2.41 metres to win the men's high jump and was close to clearing a world record 2.46m.
World and Olympic champion Sally Pearson finished down the field in seventh place in the women's 100 metres hurdles which was won by Dawn Harper-Nelson in 12.53 seconds. U.S. athletes took the first four places.
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- Athletics, Track & Field
- Asafa Powell