A championship didn’t slip from Valentino Rossi’s hands Sunday at Indianapolis Motor Speedway, but his grip on it loosened when his motorcycle slid from underneath him in the Red Bull Indianapolis Grand Prix.

What could be the pivotal moment in the season happened on lap 10 of 28 as Rossi followed race leader and Fiat Yamaha teammate Jorge Lorenzo through the first turn.

All seemed well for the six-time world champion until the bike appeared to shake briefly. In an instant he was down, banging his right elbow off the pavement as he slid to the grass.

Rossi shook his head in disbelief.

“Unfortunately I ran wide onto a dirty part of the track and lost the front end,” he said in a statement released by his team.

Rossi remounted and continued on for a few laps at a reduced pace, riding as if it was a requirement. After Dani Pedrosa, who had crashed as the leader in turn 15, went by to put him in last place, the Italian pulled off. That was lap 12.

“There was a problem with my throttle, and it wasn’t possible (to continue),” Rossi said.

“It was a bit of a strange crash,” said team manager Davide Brivio in the statement. “This is why as soon as Valentino got back (to the pits) he wanted to check the data.”

It was just Rossi’s second bad moment of the season, the other coming at LeMans in May. He finished 16th there, his only event outside the top five. Rossi has five wins in 2009; this was the first time he has failed to finish.

This miscue cut Rossi’s lead in pursuit of a second consecutive championship to 25 points with five races to go.

In MotoGP, the top 15 riders in each race are eligible to score points. Winning is worth 25 points, making Sunday’s situation a best-case scenario for Lorenzo, a two-time 250cc world champion.

“The championship is more possible,” Lorenzo said.

Rossi won his premier-class championships in 2001-05 and then again last year.

“We are still leading the championship, and that is the important thing,” he said.

Rossi started third but quickly passed Lorenzo for second as Pedrosa scooted away. Those three immediately began pulling away from the rest of the field, building a 2.5-second lead over Colin Edwards by the third lap.

But Pedrosa slid out of the lead with his low-side crash, giving control to Rossi. A year ago, it was Rossi passing Nicky Hayden on lap 14 en route to winning the rain-shortened inaugural event at IMS.

Lorenzo took the lead from Rossi at the end of the front straight on the ninth lap. Rossi braked early, giving his teammate an easier look at the first corner.

A lap later Rossi crashed, ending any chance at late-race drama.