A training-ground bust-up with Cristiano Ronaldo was followed by a bitter departure from United as boss Fergie flogged his star striker to Real Madrid - a move Van Nistelrooy believes ruined his chance on the big stage.
But after winning back-to-back La Liga titles at Real and coming out of international retirement, Van Nistelrooy is ready to take Austria and Switzerland by storm.
The Dutch master, 31, said: "I've never said I didn't want to play for the national team. Right now I'm far calmer than two years ago and that was because at United I was going through a s**t period.
"And at that time, with a big tournament, that was something I certainly didn't need. I tried hard to reject everything but it only worked to a certain extent.
"Then on top of that I had a conflict with Dutch coach Marco van Basten. Now I feel a lot better and I believe in our success."