By ESPNSTAR.com staff
The Portuguese international recorded his second successive hat-trick in Real Madrid's 4-1 mauling of Ajax in their Champions League Group D fixture last night [Wednesday].
Although critics have labelled Ronaldo as a conceited, selfish player, van Nistelrooy told Algemeen Dagblad that he never saw his former Manchester United team-mate in that light.
"I never saw him as an arrogant guy. He was always open to advice and not arrogant at all," van Nistelrooy said.
"He was a great guy in the dressing room. He was really vain, but always in a good mood and making jokes."
Recalling their time together at Old Trafford and at the Santiago Bernabeu, the 36-year old revealed that Ronaldo was obsessed with improving his skills.
"I talked to him like attackers talk among each other. A lot of his individual actions were not necessary and he lacked efficiency. He still had a lot of room for improvement," van Nistelrooy shared.
"He worked incredibly hard to become a better player, though. And that's clearly paid off. He really is crazy about the game and always wanted to become the perfect player."
Although the reason behind the Los Blancos star's recent unhappiness remains unknown, van Nistelrooy believes that Ronaldo's dedication to football is unquestionable.
"He's had to work hard to get where he is now. He put in a lot of extra hours after training. And look at where it's got him," he said.
"He is big, strong, has pace and scores tons of goals. He is a very committed professional."
Real Madrid travel to the Camp Nou to take on Barcelona in a highly anticipated El Clasico this weekend.