Driving the No. 12 Verizon Team Penske Dallara/Honda, Power passed Justin Wilson with 14 laps remaining and went on to win the 85-lap race by 1.2757 seconds over Dario Franchitti. The victory extended Power's lead in the championship race to 42 points over Franchitti with seven races remaining in the 17-race season.
"The key for me when I came to this race was avoiding carnage and accidents, which happens every year here," said Power, who also won the Toronto race in 2007. "The first corner of the first lap could have been the end for me, but I just backed off and gave up a couple of positions instead. Sometimes you just need to keep in mind the big picture."
While Power was on his way to his fifth victory in 16 starts for Team Penske, the team's other two drivers encountered problems on Sunday. While running in seventh place, Ryan Briscoe was involved in an accident on lap 61 after contact from the car driven by Graham Rahal. Briscoe continued on and finished 18th in the No. 6 Team Penske Dallara/Honda but he lost ground in the championship chase as a result of the incident. Earlier in the race, Helio Castroneves, who was battling for the race lead, collided with Vitor Meira following a lightning-quick pit stop on the 18th lap. The accident ended his day as Castroneves finished 24th in the No. 3 Team Penske machine.
With Sunday's result, Briscoe remains fourth in the IZOD IndyCar Series standings and he now trails Power by 85 points.
"That was just really unfortunate to be taken out by a non-championship contender," said Briscoe. "The Team Penske car was definitely capable of a top-five finish today and we lost a lot of valuable championship points. We were able to finish, but now we'll just have to put our heads down and get to work next weekend in Edmonton."
Meanwhile, Castroneves fell to sixth in the standings, now 92 points behind Power.
"It's very sad," said Castroneves. "We had an awesome car and I think we could've fought for the win. (Meira) just broke very early going into the turn, and I just didn't anticipate that. It's really too bad. The Team Penske crew had a great pit stop and we were looking strong. We'll regroup and come back with a better result next week at Edmonton."
Power started second and remained among the leaders throughout the race. After a late pit stop, he passed Wilson, the polesitter, on a race restart and ran strong to the finish for the eighth victory of his open-wheel career.
"It was a calculated but risky move to pass (Wilson) on the outside," Power said. "I wasn't sure I would make it out the other side. It was close. Sometimes you have to do that in racing if you want to win."
Since joining Team Penske last season, Power has finished on the podium in seven of his 16 IndyCar Series races. During that time, he's recorded 14 top-10 finishes.
"It's just the talent he has," said Clive Howell, Power's race strategist. "He can go fast when you ask him to, or he can save fuel when you ask him to. He's smart, too. He knows who he's racing out there. He put the pressure on Wilson and got by him, and we managed to beat Dario, too."
Power did so by avoiding the multitude of accidents in the race, which featured six caution periods covering 21 laps.
"I know how this race goes," said Power. "I really hung in there and waited and waited. I knew if I made no mistakes and had good stops, we'd have a chance of finishing on the podium or maybe winning. When I passed Justin, that was the key to the race."
For Power, being part of history added to the significance of Sunday's victory. "It's quite an honor to help get Penske Racing its 150th open-wheel win," added Power. "That's just an incredible feat by a great team."
It was also a special milestone for Roger Penske, who congratulated Power in Victory Circle after the grueling race. ""Will did a great job today. He ran a smart, clean race and that is what it takes to win races and championships. We are all excited to bring home the 150th open-wheel racing win for Penske Racing and we will definitely be looking for number 151 next weekend in Edmonton."
Team Penske has now won six of the 10 IZOD IndyCar Series races this season, which resumes next weekend with the Honda Indy Edmonton on the City Centre Airport circuit in Edmonton, Alberta, Canada.
Qualifying is scheduled to begin Saturday at 5:30 p.m. ET, while Sunday's race will be televised live by Versus beginning at 5 p.m. ET.