George W Bush has fallen off a Segway - a new stand-on scooter designed to make motorised travel user-friendly.
The president at least managed to keep his balance
The machine went down when he stepped onto it at his family estate in Kennebunkport, Maine, but he managed to leap to safety, landing on his feet.
The US president managed to master his lawnmower-like steed, developed by BAE Systems in Plymouth, Devon, at the second attempt and cruised around the driveway with his father George Bush Senior following closely on a second Segway.
A safety manual warns the Segway user to wear a helmet and "get a friend to act as your spotter" but Mr Bush was wearing only his tennis clothes and clutching his racket, while the nearest he had to a "spotter" appeared to be the family dog, Spot.
"If you try your first ride without a spotter, you are at greater risk of injury and you probably won't enjoy the experience as much," the manual notes.
The elder Bush's example may have done the trick
The president was not available to comment on the incident, which was caught on film, or confirm whether he had tried out the Segway before.
His foray on the new scooter follows Vice President Dick Cheney's use of a Segway to ride around his Washington office when his Achilles tendon was playing up.
The machine's creator, Dean Kamen, wants to see US Special Forces troops eventually ride Segways into battle.
But machines in use around the world at present have been mostly confined to gentle tasks such as traversing car parks or airport check-in halls.
BBC News Online journalists are currently seeing if they can triumph where President Bush failed, by taking a pair of the two-wheeled transporters out for a test ride.
See how they fared (or perhaps fell) in a report next week.