The Dutch striker joined Manchester United sporting an accessory for his long, black locks and Keane disagreed.
Van Nistelrooy was initially surprised by United captain ‘s direct approach, after a £ 19 million transfer from PSV Eindhoven.
And he disdained his headband very clearly in the early days of Van Nistelrooy.
“It was just, everybody knows that but in the beginning, I had to get used to that.
“For three months, every day he would talk about that hair band – ‘put that thing out of your head! What effect are you making with that hair band? You’re in the Premier League now! ‘
Keane was known for being omnipresent on the pitch but according to Van Nistelrooy, he was calm before the game and it was only when he crossed that white line that a switch turned.
“I remember the way he prepared for a game, it surprised me,” the 44-year-old said.
“He was just reading the program, sitting there in the dressing room so relaxed and easy.
2 hours agoIn total, Van Nistelrooy scored 150 goals in 219 games for United, winning four trophies.
He also claimed the Golden Boot in the 2002/03 Premier League winning campaign, after missing out on his starting season.
Van Nistelrooy had 23 goals and a neck and neck with Thierry Henry heading into the final day of the season but the Frenchman took home the award with a solo strike after Sir Alex Ferguson left his star player out on the last day.
Van Nistelrooy explained: “I was up there for the Golden Boot, the first year I challenged that, but in the last game of the season the gaffer left me out,” e: ‘You don’t win the son of the Golden Boot, we haven’t won the league. ‘Not even on the bench.
“The manager, it made me sharp at that point, you can’t believe it. Goals, you have to tie it with titles.”