The 37-year-old, who notched 150 goals during five seasons under Ferguson at Old Trafford, is set to become assistant manager to Guus Hiddink for the Netherlands once Van Gaal moves onto his new position.
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"Everyone will know who is the boss. He does everything himself," he said of Van Gaal while working for ESPN as a pundit for their World Cup coverage.
"Louis has assistants, but he does all the coaching - every session. He's very hands-on. He is a Ferguson-type character and it's what they need now. Louis is a good manager."
The former Red Devils favourite also believes Van Gaal will be raring to go at his new club, suggesting he will go without a holiday in order to fully assess the players at his disposal during pre-season training.
"He will start work immediately at Manchester United after the World Cup," continued van Nistelrooy. "Louis won't have a holiday. He has to start immediately.
"There is pre-season training and he has to get to know the players. Then there is the tour to America and into the Premier League season.
"He will look at the players at United and if he sees someone he likes he will give them a chance. He likes to do that. He is prepared to promote. He won't just go out and just buy players."