The best managers, with few exceptions, are usually the biggest personality in a football dressing room, but Ruud van Nistelrooy won't have any problem ticking that box at Manchester United. This is a man who made Cristiano Ronaldo cry and ended his own playing days at the club with an expletive-laden rant at then-United manager Sir Alex Ferguson.
Van Nistelrooy, who has been installed as interim head coach at Old Trafford following Erik ten Hag's dismissal as manager on Monday, earned his place in United's history books as a player as a prolific striker, scoring 150 goals in 219 appearances in a five-year period at the club before leaving in acrimonious circumstances for Real Madrid in 2006.
"In his last season, he [Van Nistelrooy] became a really difficult boy," Ferguson said in his autobiography. "I don't think he was popular by the end. Ruud had started to mouth off all the time to [assistant manager] Carlos Queiroz about Ronaldo. There were a few stand-up confrontations."
Those confrontations included forcing Ronaldo to tears in a training ground bust-up shortly after the young forward suffered the loss of his father and a moment during the 2006 EFL Cup final, after Van Nistelrooy had been dropped by Ferguson to the bench, when he reacted angrily to the manager's decision not to give him game time.
"'You s---,' said Van Nistelrooy. I'll always remember that," Ferguson revealed in his autobiography.
So how much of this matters almost 20 years on? Van Nistelrooy and Ferguson have long since patched up their relationship, and the 48-year-old has said that he and Ronaldo have since "figured it out" and now have a "perfect relationship."
But while the events from his playing days at Old Trafford are now water under the bridge, Van Nistelrooy's character hasn't changed. He is still a big personality, somebody with the high expectations you would associate with a former United and Real Madrid player, and he still does things his own way.
With Van Nistelrooy now tasked with a new role at United, we take a closer look at why he was brought in to begin with, what can we expect from his style and whether he can change things at Old Trafford.
Van Nistelrooy's coaching style and background
When Van Nistelrooy resigned as PSV Eindhoven coach the day before the final game of his only season in charge in 2022-23, sources in the Netherlands told ESPN it was because he felt he was not backed by the club's hierarchy.
There were reports in the Netherlands that several players had complained to senior figures about Van Nistelrooy's coaching style and his tactics, although sources have told ESPN that Cody Gakpo and Xavi Simons, two young players under Van Nistelrooy at PSV, regard him as a significant influence on their careers.
PSV finished Van Nistelrooy's solitary season as KNVB Cup winners and with a Champions League qualification spot as runners-up in Eredivisie behind Arne Slot's Feyenoord. Sources have said that, due to PSV's defensive weaknesses, Van Nistelrooy set up his team to play a counterattacking style -- a pragmatic decision over his preference for a more expansive style based on the realities of the players at his disposal. But despite his self-belief and the certainty of his own approach, Van Nistelrooy's coaching journey has been one of somebody prepared to listen to and learn from other sources.
He has twice worked alongside more experienced coaches, in Guus Hiddink and Ronald Koeman, as part of the Netherlands international team set-up and prior to taking jobs in the youth set-up at PSV, where he worked with the Under-17s, Under-19s and reserves, Van Nistelrooy spent a year on the road, watching and studying training at Real, Boca Juniors and River Plate.
He is tough, ambitious, single-minded and a much harder character than the last United great -- Ole Gunnar Solskjaer -- to take on the interim job. Maybe Van Nistelrooy is just what United need right now. But if he isn't, don't expect him to do things any way other than his.
Why Man United picked Van Nistelrooy
His move to United this summer to work as Ten Hag's assistant might have been viewed by Van Nistelrooy as another chance to learn from a more experienced coach. He accepted that job ahead of the chance to return to management with Burnley, following the departure of Vincent Kompany to Bayern Munich after the club's relegation from the Premier League last season.
Van Nistelrooy and Ten Hag had no previous experience of working with each other, and it was an appointment driven by United's new INEOS-led football hierarchy. And although Ten Hag spoke positively of the appointment at the time, there was also perhaps a sense that United were lining up Van Nistelrooy for precisely the role he now occupies -- a reliable back-up should Ten Hag fail again.
Now, Van Nistelrooy must work with an underperforming team ahead of Sunday's home game against Chelsea sitting 14th in the Premier League table.
It helps that he has already gained the respect of the players who must now call him "boss." ESPN reported earlier this month that Van Nistelrooy has been holding one-on-one meetings with players and that he "looks and acts like a manager." One source said of Van Nistelrooy that he "has an aura about him."
Rob Dawson examines the potential replacements for Erik ten Hag at Manchester United.
That comes from his playing pedigree but also his personality. Ten Hag was deemed to be a studious, teacher-like figure, unlike Van Nistelrooy, who possesses the swagger of somebody who performed at the top of his profession.
Van Nistelrooy's coaching career has been so brief that it would be difficult for United to spin the line that they had hired him for his potential as the next big thing, however. Van Nistelrooy's big selling point was his status as a significant former player and one who has remained hugely popular with the club's supporters.
And he hasn't shied away from the fans' adulation. After a 3-3 draw against FC Porto in Portugal earlier this month, Van Nistelrooy was the last United figure off the pitch as he acknowledged the supporters singing his name. Acknowledged their supporter or milked the adulation -- take your pick, depending on your point of view.
Most other assistant managers would make a hasty exit to avoid accusations of undermining the manager, but Van Nistelrooy has always done things his way and this was another example of that.
It will be the same when he picks his team and names his tactics. If some players don't like it, Van Nistelrooy won't care.
Can Van Nistelrooy make a difference?
This is the difficult part. If United's situation was a quick fix, Ten Hag would still be in charge and preparing for this week's home games against Leicester (EFL Cup fourth round) on Wednesday and Chelsea (Premier League) on Sunday. But the reality is that United are in an almighty mess and Van Nistelrooy has to somehow find a way to spark a change of fortune.
At PSV, Van Nistelrooy successfully played the cards he was dealt, and doing that at United would be a good start. If he takes the same pragmatic approach, he will use players in their best positions, with no more of the bewildering selections made by Ten Hag, such as using full-back Noussair Mazraoui in the No. 10 role against Fenerbahce or taking central midfielder Manuel Ugarte in and out of the team.
United are a team that fades in the final 20 minutes of games -- it was a problem throughout Ten Hag's time charge -- so Van Nistelrooy will need to work on the squad's fitness, but also their concentration levels.
One area where Van Nistelrooy has a clean slate, however, is with the players. Several of United's first-teams stars had difficult relationships with Ten Hag and it showed in their performances, but with Van Nistelrooy in charge, he can exploit that sense of liberation among the players, even if it only lasts a few games.
Marcus Rashford and Bruno Fernandes are two players who have not performed to their expected levels, so if Van Nistelrooy can get them playing well, United can bounce back and start winning games again.