The mass injury return at Manchester United raises alarm, despite it being a positive occurrence ahead of a fresh start under Ruben Amorin.

The atmosphere at the Theatre of Dreams is filled with optimism and determination as players and the new set of coaching staff look to get the new era underway in the best fashion possible.

Ahead of the return of club football this week, Ruben Amorim held his first training session with the team on Monday, and the turnout was quite impressive, with a lot of first-team players involved despite the ongoing international break.

Manchester United had a terrible injury record under Erik Ten Hag, but a few weeks following his departure, almost everyone is fit and back in training, ready to step onto the pitch again when play resumes.

In the final weeks of Erik Ten Hag’s departure, around ten first-team players were absent from the team, and almost all of them returned to training for Ruben Amorim’s first game. Is this an innocent coincidence?

But as much as this is good news for Manchester United and Ruben Amorim, it does expose the players' desires to rebel, and if it happened during the reign of Erik Ten Hag, then Ruben Amorim should watch his back.

Since the departure of Sir Alex Ferguson in the summer of 2013, many of the managers let off by Manchester United have failed as a result of players' rebellion.

More than a decade later, it has turned into a cycle. Albeit it wasn't the highlight of Ten Hag’s departure, recent activities tell different stories.

Manchester United players who return to training

Leny Yoro represents a very positive update for the club. The highly-rated young center back is yet to make his official debut for the club since completing his big-money move from Lille in the summer.

He sustained a back injury in a preseason friendly clash with Arsenal in the summer, missed four months, and failed to play under Ten Hag, who was the manager who brought him to Old Trafford.

He returned to training and is now expected to be available for selection when play resumes this weekend, and Ruben Amorim gets his reign underway with an away trip to newly promoted Ipswich Town.

Luke Shaw was also in training. The Englishman has not featured at all this season, having been ruled out with a calf injury since August, although he featured for the Three Lions in the European Championship, he hasn't played for the club since February.

The 29-year-old was one of the most important players in Ten Hag's first season, making 47 appearances across all competitions. However, he has only played 15 times since the start of last season.

To worsen matters, his alternative in the leftback position, Tyrel Malacia, who also returned to training, was a consistent absentee. Hasn't played a game since the start of last season.

Kobbie Mainoo, who offered relief amidst the tough period, also picked up an injury early in October, and the consequence was grave as the Dutch manager lasted just three games without him.

The 19-year-old is also back in training and expected back in action when play resumes. Other players who picked up minor injuries lately are also back in training, Mason Mount and Antony.

Harry Maguire and Victor Lindelof, the latter whom suffered a leg injury while playing for Sweden against Slovakia during the international break, remain the two first-team players on the injury list at Manchester United.

The signs are great at the start, just as it was when other managers started their reign, so it is no reason to get carried away.

In addition, the likes of Marcus Rashford, who was very underwhelming for a significant period under Erik Ten Hag, have also been active on social media following the first session under Amorim, commending the ways of the Portuguese.

That is how it started against the past managers, too, so Amorim has to learn and know the ways that work well around the club, and safeguard himself.

A huge task awaits the Portuguese tactician in Old Trafford, and although the pressure has been calmed by Ruud van Nistelrooy, the early days don't matter, but they will decide the end, and how long his reign will last.

He will need to lecture on getting the job done while doing the difficult job of keeping things together at a club where rebellion has denied his predecessors the chance to succeed in the long term.