Gary Neville has urged Manchester United to cut out their complacency or risk their season being over ahead of a pivotal month of fixtures.
The Red Devils overcame their first test on Sunday afternoon, winning 4-2 at bitter rivals Leeds United in the Premier League.
Manchester United led two-nil at half-time before two goals in 24 seconds saw them pegged back at Elland Road. Luckily for Ralf Rangnick's side though they responded from that setback to regain their two-goal cushion and seal victory.
However, those mad-cap seconds at Elland Road in which their two-goal lead vanished is what worries Neville.
United's next game is the first leg of their Champions League last-16 tie at Atletico Madrid on Wednesday night before they then host Watford in the Premier League.
After the Hornets, they then face a brutal run of fixtures against Manchester City (A), Tottenham (H), Atletico Madrid (H) and Liverpool (A).
'Manchester United do have vulnerabilities. The test is now the next month,' Neville said on his The Gary Neville Podcast on Sunday. 'This period was always going to come and it is here.
'That was the start of it and I thought it was a really difficult game. Leeds are a team who do invite you on to try and score goals against them, but it is still one of the most difficult places for Manchester United to come.
'They have got to stop those mad moments, those five-minute periods where they concede two goals, because if you concede two against City, Liverpool or Atletico, you are out of the game.
'I think this [the game against Leeds] is a warning sign.'
Neville's remarks come at a time when there has been reported issues of disharmony within the squad.
Last week, Christian Falk head of German publication Sport Bild, reported that all is not well within the United dressing room - with Cristiano Ronaldo causing factions.
Taking to Twitter, Falk wrote: 'English players like Harry Maguire, Marcus Rashford & Co are irritated that Ronaldo wants to lead the dressing room with his own clique. There is a risk of a split in the team @ManUtd'.
This followed reports by Spanish outlet AS claiming that Ronaldo's relationship with interim boss Rangnick is completely fractured.
AS claim that the five-time Ballon d'Or winner believes Rangnick does not have the ability to manage United and is out of his depth at Old Trafford.
And to make matters worse, Rangnick is said to have angered Ronaldo further on February 11, after he accused the forward of not performing in front of goal.
Other attempts from elsewhere in the dressing room have been made to undermine Rangnick and his coaching staff.
Earlier this month it was claimed that some United players refer to Rangnick's No 2, Chris Armas, as Ted Lasso - the hapless coach in an Apple+ TV series.
