Read more - Oracle claim first blood against Team NZ
"I think there are a couple of bruises and a bit of compression damage to the hull, maybe the fairing on the starboard side," observed Japan tactician Chris Draper. "I was quite surprised, it was pretty dramatic stuff.
"From my point of view, I was amazed at how late they reacted and when they did react, there was a big sideways skid.
"It was good both teams managed to keep racing and have a good battle."
Sir Ben Ainslie is quickly developing a reputation for his on-the-water misadventures, after colliding with Team NZ in practice last week, forcing the Kiwis off the water for several days.
The collision marred what could have been a successful day for BAR, which entered the challenger regatta with a two-point advantage, carried over from their success in the America's Cup World Series.
Despite their shaky form during the Bermuda build-up, BAR had earlier upset Team Sweden, one of the challenger favourites, in their first race of the day and were probably licking their lips at the prospect of toppling Japan as well.
It was not to be.
Earlier, Sweden had out-manoeuvred Japan, guided by former Team NZ skipper Dean Barker. for a 13-second victory.
Barker had his boat 17 seconds ahead at the fourth mark, but Sweden skipper Nathan Outterridge turned that deficit into a 19-second advantage by the next turn, forcing Japan off their course with a rules challenge.
"The key to that was just keeping it close the whole race," said Outteridge afterwards. "Dean seemed to misjudge that tack position and we made the most of it."
But the Swedes could not celebrate long - they were beaten by Great Britain in their second race of the day for perhaps the first real upset of the regatta.
Day one results:
Oracle Team USA bt Team France delta - 2m 11 s
Artemis bt Team Japan delta - 13s
Emirates Team NZ bt Team France delta - 2m 33s
Ben Ainslie Racing bt Artemis - 11s
Oracle Team USA bt Emirates Team NZ - 6s
Team Japan bt Ben Ainslie Racing - 48s
America's Cup Qualifiers leaderboard
Oracle Team USA - 3pts (1 point carried over from ACWS)
Ben Ainslie Racing - 3 (2 points carried over from ACWS)
Artemis - 1
Emirates Team NZ - 1
Softbank Team Japan - 1
Groupama Team France - 0