INDIANAPOLIS (AP) – This was a race with the weather. Which would come first, the rain or the end of the Indy 500?

Dario Franchitti gambled on the rain and won Sunday, another bittersweet day for the Andretti family at America’s richest race.

The Scotsman, one of five Andretti Green Racing drivers in the field, took the lead when the leaders pitted one last time for fuel despite darkening skies, and then drove slowly to the checkered flag in a downpour when the race was stopped after 166 laps, or 415 of the scheduled 500 miles.

“Our roll of the dice proved to be the lucky one,” a jubilant Mr. Franchitti said. “I made a couple of good restarts and the rain came.”

None too soon by Franchitti’s reckoning.

As the dark clouds drew ever closer, crew chief John Anderson told him on the radio, “The rain’s eight blocks away.”

“Come on!” Mr. Franchitti said. “I was just hoping it would start soon.”

The race had already been interrupted by rain for three hours shortly after the midway point, and Franchitti won it under a caution light brought out when teammate Marco Andretti crashed three laps from the premature finish.

Mr. Andretti, who lost this race last year as a 19-year-old rookie when Sam Hornish Jr. passed him on the final straightaway, had slipped into the pack and was trying hard to move back into contention when he tried to make a pass in traffic and came together with 2005 Indy winner Dan Wheldon on the back straightaway.

Mr. Andretti’s car veered hard into the outside wall, slid back across the track in traffic and flipped on its top after it hit the infield grass. It finally came to rest on its wheels and Andretti was able to climb out uninjured.

“I’m one lucky guy,” Marco said. “I’m so proud of Dario Franchitti.”

Mr. Franchitti made a victory lap of the 2.5-mile oval in the heavy rain as actress wife Ashley Judd, soaking wet in a summer dress, climbed the pit wall and dashed toward the victory celebration.

Once Mr. Franchitti got out of his car, he was mobbed, hugged and kissed by teammates Tony Kanaan, his best friend, Danica Patrick and Michael Andretti.

“I can’t believe it. It’s the Indy 500!” Mr. Franchitti said. “To be a member of this club is fantastic. I kind of have half of an idea of what it means to win this race. I’m so happy.”

Mr. Franchitti’s average speed was 151.774 mph, far from the record 185.81 mph by Arie Luyendyk in 1990.

Scott Dixon was second, followed by Helio Castroneves and Sam Hornish Jr. The rest of the top 10 were Ryan Briscoe, Scott Sharp, Tomas Scheckter, Patrick, Davey Hamilton and Vitor Meira.

It was Andretti Green’s second victory in three years, but that’s about all the good luck the Andrettis have had at Indy since Mario Andretti, Marco’s grandfather and Michael’s father, won in 1969.

Mr. Kanaan, had appeared in control when rain poured down the first time after 113 laps, just four laps after he took the lead with a pass on Mr. Andretti.

Mr. Franchitti was fifth when the race resumed and fell all the way to 14th after a pit stop to replace a tire following the restart. After that, Mr. Franchitti had a very fast car indeed. He began to move through traffic under the green flag, getting to seventh on lap 131, just before the leaders began making green flag pit stops.

Mr. Franchitti regained the lead on lap 137 when Kanaan and Patrick pitted and stayed out front until he pitted on lap 143. At that point, Kanaan got back out front and appeared headed for the victory he thought he had when the first rainstorm hit.

But after Marty Roth crashed, bringing out another yellow flag – and even knowing rain was moving closer – Messrs. Kanaan, Hornish and the other leaders chose to pit for fuel and tires on the 155th lap. Franchitti stayed out and led the rest of the way.

“That’s the Indianapolis 500,” said Mr. Castroneves, a two-time Indy winner. “You bet it all. Dario took a gamble. He’ll be happy with the result and the paycheck.”

Any chance Kanaan had to win evaporated on lap 156 when Jaques Lazier crashed in front of him and Kanaan spun, barely avoiding the inside barrier near the pit entrance. He rolled into the pits with a flat tire and was later penalized when his crew changed all four tires in a closed pit, instead of just the one that was flat. He wound up 12th, just ahead of team co-owner Michael Andretti.

Ms. Patrick was the only one of the three women in the field to have an impact. Milka Duno ran no higher than 22nd before crashing after 65 laps and ending up 31st, and Sarah Fisher finished 18th, two laps behind.