Usain Bolt gave Moscow's Luzhniki Stadium a split-second scare before jogging to victory in his 100 metres heats at the World Championships.
The Jamaican dramatically false-started in the final in Daegu two years ago, leading to a disqualification, and there were gasps around the arena when the recall gun went again - but this time Bolt was not the guilty party.
After seeing Kemar Hyman of the Cayman Islands leave the track, the world record-holder made his customary slow start before pulling clear and easing down to win in 10.07 seconds.
James Dasaolu, the second fastest Briton in history after his 9.91secs run earlier this summer, had considerably more to sweat about as he had to rely on the final fastest loser spot to progress.
Dasaolu has been plagued by a hip problem in recent weeks and it showed as he started slowly before going on to finish fourth in 10.20s.
Dwain Chambers and Harry Aikines-Aryeetey made it a full complement of Britons into the semi-finals.
American Mike Rodgers was the fastest qualifier in 9.98.
Dasaolu said: "I haven't had the best of preparations since my 9.91. I had a hip problem when I had to pull out of the Anniversary Games. It's been my first time out of blocks for two weeks, and I didn't know where I was coming from as I haven't been able to train as much.
"I just hope I correct a few things and do myself justice at these champs.
"I thought I had third in the bag and I eased up to save energy like you do through the rounds - I'm glad it hasn't cost me a spot in the semi-finals.
"It felt all right, I had no pain and no problems, it took a bit of time to get it to where it needed to be but now I'm pain free.
"I'd like to believe I can race better. My body will adjust overnight and I'll step my game up - it was just rustiness."