The incident occured in breezy conditions of around 16-19 knots on the Great Sound, but still well within the range in which the yachts will be expected to perform in the regatta, which gets underway on May 27. The upper wind limit for the America's Cup is 24 knots.
The drama occurred as the team were trying to pull off a high-speed foiling gybe. As the team rolled through the gybe, the 50-ft catamaran kept turning and spun out, tipping onto its leeward hull. The four crew members in the leeward hull were forced to cling on while the hull became submerged.
The catamaran was swiftly righted and observers in Bermuda noted USA-17 returned to the team's base without obvious damage.
The team later issued a brief statement on their website: "Oracle Team USA capsized during a practice session focused on pre-start maneouvres.
"The boat was righted within three minutes and there were no injuries to the crew or damage to the boat."
Yesterday's incident follows two major scares for the team during training last month - the first resulted in a near capsize, and the second, the following day, triggered a full capsize.
While Oracle are the only team to have capsized their race boat, almost all of the challengers have experienced hair-raising moments of their own in the high-powered, but extremely skittish, wing-sail catamarans.
Emirates Team New Zealand had a scare in one of their first few days of sailing up in Bermuda, nose-diving after catching a gust of wind as they attempted the tight harbour exit. There were more nervous moments for the team earlier this week, when they almost achieved full lift-off as the bow of the boat reared up.
