SPARTA, Ky. (AP) The battle for the Indy Racing League championship is almost as close as Felipe Giaffone's victory over Sam Hornish Jr.

With a different winner in each of the past nine races, the points battle is a four-way shootout that might not be decided until the season finale at Texas next month.

"The championship is very open," said Giaffone, who held off Hornish by 0.0932 seconds in the Belterra Casino Indy 300 on Sunday.

It was the first career victory for Giaffone, who was the IRL rookie of the year last season and has been one of the league's most consistent drivers with Top-10 finishes in all but four of his 25 career starts. He was second at Nazareth, Pa., in April and third at Indianapolis in May.

"After Indianapolis, where I really felt that I had the car to win, I said, `Oh, man, even if I win a race I'm not going to be happy because I'm so mad.

"I can tell you," he said of his emotions now, "it's completely different."

Hornish, the defending IRL champion, took over the series lead with 399 points, just four ahead of Helio Castroneves. Gil de Ferran, who went in as the points leader but finished 21st, dropped to third with 386 points and Giaffone is next with 382 - a margin of 17 points separating the top four drivers with three races to go.

"It's so tough. It just shows how competitive the IRL is," Hornish said. "It's tough to gain an advantage in the points because a new guy wins and he starts building on his points."

During practice for an Infiniti Pro Series race earlier in the day, actor Jason Priestley's race car crashed head-on into a wall at nearly 180 mph, breaking his back and leaving him in serious condition with a concussion and other injuries.

The former "Beverly Hills 90210" television star was flown to the University of Kentucky Medical Center with a spinal fracture in the middle of his back and a closed head injury, as well as broken nose and broken bones in his both feet, IRL medical director Henry Bock said.

Giaffone, a 27-year-old Brazilian, led 124 of the 200 laps on the Kentucky Speedway tri-oval and won $125,200 from a purse of $1.053 million.

"It was one of those weekends when everything works great. We had a great car, and even in the warmups I said, `We don't have to change a thing."'

Giaffone led the final 39 laps after the leaders made their final pit stops for fuel.

Hornish dropped to third as the race seemed to come down to a battle between Giaffone and Buddy Lazier, the two-time defending race winner. But Hornish passed Lazier for second place with four laps to go and pulled within 0.041 second of Giaffone going into the final lap.

Giaffone was able to pull around slower traffic and beat Hornish to the checkered flag.

"Sam showed he had a strong car," Giaffone said. "And that was my question: Is that it, or does he have something left? For sure, my car was great, but he could manage to run behind me, side-by-side, everywhere."

Lazier was third, followed by Scott Sharp, Castroneves and Al Unser Jr., who missed the past two races while undergoing treatment for alcohol abuse.

Lazier, whose brief lead midway through the race was his first since he won here a year ago, said he didn't have enough power to get by Giaffone late in the race.

"I'd get a run on him, and he did a good job defending. My only chance at the end was lap traffic hopefully clogging up the first two guys and I'd get a run on them, but I didn't quite have the legs for him."

Sarah Fisher, the first woman to start from the pole in a major racing series, led the first 26 laps and finished eighth.

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