The American quartet had been favourites to take gold

Mardy Scales and Leonard Scott made a mess of the first changeover, the baton eventually ending up on the floor.

"The bottom line is that it slipped out of my hand," said Scott. "It was my fault. I put the blame on myself. It's too bad it had to happen."

Olympic champions Great Britain safely advanced to Saturday's final.

The quartet of Jason Gardener, Marlon Devonish, Christian Malcolm and Mark Lewis-Francis qualified from heat two behind Trinidad and Tobago in 38.32 seconds.

"We're pleased to get through but there is room for improvement," Gardener told BBC Sport.

I ran well and got rid of some demons Mark Lewis-Francis

Britain are expected to keep the same line-up for the final despite injury concerns over Lewis-Francis.

"I ran well and got rid of some demons," said Lewis-Francis, who failed to reach the 100m semi-finals because of a recurring hamstring problem.

"If I have to go out there and push it then I will. We will go out and seize the day."

Gatlin, who became just the second athlete to win both the 100m and 200m world titles, was at a loss to explain what happened to his American team-mates.

"It's disappointing because I had high hopes I would go out and bring home the gold," he told BBC Sport.

"We have been practising a lot but maybe we switched the team more than we needed to. It was more of a jittery thing."