All four of Power's victories have come on street or road courses. The series leader — 42 points ahead of Franchitti — won two weeks ago at Watkins Glen and swept the season-opening road races in Sao Paulo and St. Petersburg.

“As I predicted, it was a very wild race,” said Power, second on the starting grid behind Wilson. “It started on the first corner for me when I had Helio (Castroneves) and (Ryan) Hunter-Reay come cruising up the inside. I was like, `OK, I'll let those guys go.' And then I lost a couple of more positions. But I know how this race goes.

“The key for me when I came to this race was avoiding carnage and accidents, which I know happens every year, and like I said, in the first corner, that right there could have been the finish if I'd just turned in. But I backed off.”

The Australian is in his first full season with Team Penske after driving six races last season, highlighted by a victory in Edmonton. Before shifting to IndyCar, he won three Champ Car races, including the 2007 race in Toronto on the tight and bumpy, 11-turn, 1.755-mile Exhibition Place track.

Power gave Roger Penske his 150th open-wheel win and 41st in the IndyCar Series.

“They give me the equipment to win,” Power said. “I have a full-time ride with one of the best teams in the series, so to pay them back, you've got to win. We'll always be challenging for wins every weekend and we should be. It's as simple as that.” Power finished 1.2757 seconds ahead of Franchitti.

Hunter-Reay was third, followed by Tony Kanaan, Graham Rahal, Danica Patrick, Wilson, Marco Andretti, Simona de Silvestro and Dan Wheldon.

Franchitti gave up the lead to pit with 30 laps left, and Wilson and Power made their final stops a lap later. Wilson beat Power out of the pits and they both ended up ahead of Franchitti. After the fifth of sixth caution periods, Power got past Wilson on the outside. Wilson spun out moments later and dropped from contention.

“The tires got a lot of pickup (rubber from other tires) and were cold and I knew everyone was going to be struggling and that there'd be a lot more chances of people making mistakes,” Power said.

“And that's what he (Wilson) did on the restart. I'd say it was a calculated, but risky, move to pass him on the outside. ... Sometimes you have to do that in racing if you want to win.”

Franchitti finished second a year after winning the race — holding off Ryan Briscoe and Power on a late restart — en route to the season title. The Scot also won a Champ Car race in Toronto in 1999.

“I had to pit a lap early, so Justin and Will jumped ahead when they went a lap longer,” Franchitti said. “We just didn't run quite quick enough. We were fast in practice, but weren't quite fast enough to beat Will.” Patrick was pleased with her sixth-place finish, her best result in the first six street and road events of the year.

“It's a great confidence booster,” Patrick said. “We were really happy with the way the car was performing throughout the whole race.”