Americans Nicky Hayden and Ben Spies both made competitive starts to their home Indianapolis MotoGP round - but also both crashed.
Hayden was first to become unintentionally separated from his machine, sliding off his factory Ducati at high-speed through turn 13 with 13 minutes of the hour to go.
Concern was raised about Hayden's left arm, which he was examining in the aftermath, but it turned out to be nothing worse than a friction burn caused by trying to protect the wrist he chipped last time out at Brno.
Hayden returned to the track in the closing minutes and, although he didn't improve, still finished the session third fastest, behind only his team-mate Casey Stoner and MotoGP title leader Jorge Lorenzo.
"At the start of the session I was feeling really good and I was going quite fast on a hard tyre. When we put the soft tyre in I felt even better and maybe got a little too excited because that's when I made a mistake," explained Hayden, who took his only Ducati podium to date at Indianapolis last year.
"I was off line a little but I didn't force it, I just let it go because it's only first practice but 'bam'! I was down immediately. It was a bummer because my suspension guy had come up with some settings that were working really good and I really liked the feel.
"At least I didn't do any more damage to the wrist - all I got was a friction burn on my arm from digging it in trying to save the wrist. It's nothing major though and after finding a good base setting today I'm looking forward to possibly trying the new forks tomorrow."
Spies suffered a similar fall, at turn six, with just a handful of minutes remaining. The Monster Yamaha Tech 3 rookie was also unhurt, but his session was over and he dropped from sixth to eighth after the tumble.
"I'm actually pretty happy with that session even though it ended not so great with the crash," said Spies. "I'm not too upset because it was one of those crashes that I know what I did wrong. There's a bump going into turn six and I turned in a little too early.