It brings to an end the Dutchman’s reign at Old Trafford after just two-and-a-half years but that’s still longer than some expected given that he was close to losing his job over the summer.
Despite a worst-ever finish in the Premier League last season, United ultimately stuck with Ten Hag after he masterminded an FA Cup final win over rivals Manchester City.
The club will hope that Van Nistelrooy can spark an immediate uptick in performances, but Keane has insisted that the players must also take the time to hold themselves accountable for their part in the poor start to the season.
Posting a selfie on Instagram, the former United captain wrote: ‘In good teams, coaches hold players accountable. In great teams, players hold players accountable.’
Rio Ferdinand, meanwhile, has questioned whether the club will now be regretting their decision to not hire Thomas Tuchel in the summer.
The German had been heavily linked with the Red Devils before the FA Cup final having just left Bayern Munich and was keen on a return to English football.
The former Chelsea boss remained linked with Old Trafford up until just two weeks ago when he was announced as the new England manager, replacing Gareth Southgate.
Reflecting on Ten Hag’s departure on Monday, Ferdinand thinks his former club should have acted sooner to land the ideal replacement for Ten Hag.
‘My big thing is it’s taken so long,’ he said on his YouTube channel. ‘One of the best candidates that was sitting out there was Thomas Tuchel and he’s gone now, he’s become England manager.
‘England fans will be delighted with that but I think Man United will be looking at that and saying “Is that one that got away?”.’
Van Nistelrooy, given a chance to impress as interim boss, is the early favourite to succeed Ten Hag on a full-time basis, with the likes of Thomas Frank, Gareth Southgate, Julian Nagelsmann and Sporting boss Ruben Amorim also contenders.
Ferdinand is backing former teammate Van Nistelrooy to do well but says he could also see former Barcelona boss Xavi at Old Trafford.
‘I’d probably give it to Ruud right now. He’s in the hot seat,’ he added.
‘He’s seen the place, like I say, it’s not going to be a big upheaval in terms of knowing and getting to know the players. He knows them all right now.
‘But Xavi, if we could get someone like him. Playing football the way Barcelona did with that aggressive football.
‘He won the league when he was at Barca, introducing young players into the team. He brought through Lamine Yamal. That’s what Man United’s DNA is about.’