Justin Wilson was relieved to score his maiden IndyCar victory at Detroit yesterday after a troubled first season in the unified category.
The Briton ran second for most of the race and took the lead when Castroneves was ordered to let him past after being adjudged to have blocked Wilson's attempt to take the lead after the final caution period.
He was delighted with the result after what has been a tough year and now lies 11th in the standings.
"It's been tough to keep going and saying 'that's racing, that's racing' when it isn't going well, but you've got to keep picking yourself up and moving on," said Wilson.
"I'm very happy to have finally got a win this year and keep my streak going of winning at least one race every season."
Wilson admitted he would have been tight on fuel at the end, but the final caution period allowed him to attack Castroneves and drive flat out to the end of the race.
"We pitted quite early on the last stop because the team saw some debris on the front straight, so that put the pressure on knowing that we'd given up five or ten laps of fuel," he added.
"I didn't think it was going to be possible, but fortunately that yellow came out and allowed me to run hard again. I got the call that I could go flat out and that's when I decided to push hard."
He also paid tribute to Newman/Haas/Lanigan team co-owner Paul Newman, who is reported to have been treated for cancer this summer.
"Paul is a great part of the team, he calls me after every single race and passes on his regards to how well we've done or how unlucky we've been," said Wilson. "It's great to finally be able to repay his comments and nice words.
"It's amazing to finally get a win for Newman/Haas/Lanigan. This is definitely the highlight of my career. We've got three fantastic owners who all add something to the team in their own unique way and I'm very privileged to be driving for them."