Former Manchester United star Gary Neville and fans has blasted the team's owners for the way manager David Moyes was sacked.
Neville said that Moyes should have been given more time before his ousting.
The Manchester United Supporters Trust said the manner of the sacking was a "PR shambles" because of media leaks about the sacking.
United's American owners, the Glazer family, ousted Moyes after less than 10 months in the post, with the team slumping in the Premier League and Europe's Champions League.
"The last 15, 16 hours or however long it's been, I don't like it, it's not the way in which the club should portray itself," Neville, who won eight Premier League titles with United, told Sky Sports.
"But it's the modern world, it's how things seem to be dealt with now, but I'm a traditionalist and I think it could have been dealt with a whole lot better.
"I believe in managers being given time, I think they should be allowed to complete their work."
But Neville added that Manchester's results this year have been "poor".
"As a fan I've not enjoyed watching it -- I'm sure David Moyes himself hasn't enjoyed watching it."
Neville said Manchester United players must "take massive responsibility" for the bad season.
"I never once during my 17/18-year career at United turned around after a game and thought 'you lost us that game boss'.
"It's always the players. Players have to take responsibility, accountability in football."
Sean Bones, vice chairman of the Manchester United Supporters Trust, expressed outrage at the way British newspapers knew about the impending sacking on Monday, calling it a "PR shambles" for the club.
"The story leaked before David Moyes has been spoken to, and that's not the Manchester United way. There was no dignity or class in the way they went about it."
Former United and England striker Michael Owen said the club may have had no choice but to act now.
"With the summer looming and a huge transfer kitty available, United had to be 100% (certain) Moyes was the right man," Owen said on his Twitter account.
"Evidently they didn't have the confidence in him in which case makes the timing absolutely right. Now the big question is who's next?" he added.
Dwight Yorke who played in United's team which won the Champions League, Premiership and FA Cup, believes interim manager Ryan Giggs could be the person to take permanent charge.
"There is never going to be someone like Sir Alex Ferguson but what we're given here is a young manager who is looking to break in," said Yorke.
"He's not got the managerial skills but we thought that David Moyes had those skills going into Manchester United with the experience that he had for 11 years being at Everton and the wonderful job that he'd done.
"But he hasn't been able to turn things over at Manchester United.
"I think for togetherness and getting the results and playing a certain way, a brand of football that is more eye-catching, the Man United way, I feel that Ryan Giggs is the right person."
JURGEN KLOPP
Klopp has certainly caught the eye on the European stage in recent years, guiding his dynamic Borussia Dortmund side to the UEFA Champions League final in 2012/13 off the back of the Bundesliga titles they won under him in each of the previous two seasons. The German is a charismatic, young coach and would surely prove a popular choice among United fans.
LOUIS VAN GAAL
The Netherlands coach has a vast amount of top-level experience and success on his CV, having previously been in charge of Bayern Munich, Barcelona and Ajax, and has been heavily linked with both United and Tottenham of late.
DIEGO SIMEONE
Another youthful coach who has rapidly risen to prominence over the past few seasons, former Argentina international Simeone led Atletico Madrid to the UEFA Europa League title in 2012 and has overseen their run to the Champions League semi-finals this campaign, while it is also currently leading the Primera Division ahead of Barcelona and Real Madrid.
LAURENT BLANC
Blanc won the Ligue 1 title as Bordeaux coach and looks set to secure it again this term with Paris St Germain, having had a stint in charge of the France national team in between. The fact that he spent time at Manchester United at the end of his playing career would likely count in his favour in terms of how he would be perceived by the club's supporters.
RYAN GIGGS
There are few players as revered among the Old Trafford faithful as the 40-year-old Welsh midfielder, who is already part of the current United coaching staff on top of being a squad member. There would be considerable goodwill towards him from fans if he were to land the top job, but he lacks management experience. He looks a likely candidate to take the job on an interim basis, if not permanently.
SIR ALEX FERGUSON
The 72-year-old Scot, who has stayed on at the club as a director since finishing as manager, returning to the hot seat so soon after selecting Moyes to be his successor would certainly be interesting. Whether Ferguson would even entertain the idea is very much up for debate, as is the issue of what his comeback would mean for United in the long-term, given the age-old question of 'how do you replace Fergie?' would be straight back on the agenda
