Despite only returning to Old Trafford in a two-year deal over the summer, the five-time Ballon d'Or winner could walk out the door at the end of this season.

To say Manchester United are in turmoil would be an understatement. However, things could get worse for the club, depending on how you feel about the club's decision to resign Cristiano Ronaldo, as British tabloid The Sun reports that the Portuguese icon could leave Old Trafford this summer.

Despite only sealing a widely-celebrated return to Manchester last summer, the five-time Ballon d'Or is already pondering prematurely ending his second spell with the Premier League giants. The attacker joined from Juventus on a two-year deal and while he initially hit the ground running, things have taken a turn for the worse both for him and the club.

The 20-time English champions were tipped to challenge for the league crown this season, having last won it in Sir Alex Ferguson's final year in charge in 2013. However, with Ole Gunnar Solskjaer being sacked and Ralf Rangnick struggling to implement his style of play so far, Manchester United find themselves in the midst of a top-four battle, with the Red Devils being in grave danger of missing out on UEFA Champions League football next season.

Here lies one of Cristiano's biggest issues at the club. Having played under the iconic Sir Alex and numerous world-class teams, both at the Theatre of Dreams and at Real Madrid, the player has been shocked by the drop in quality at Old Trafford. The likes of Manchester City, Liverpool, and Chelsea have moved miles ahead while the Red Devils continue to struggle both on and off the pitch.

Ronaldo recently gave an interview with Sky Sports in which he criticized the players and their lack of determination to reach the best. This is evident from the table, with Guardiola's league leaders sitting a whopping 21 points ahead while West Ham and Arsenal currently rank above them in the top-four race.

The European giants are out of both the Carabao Cup and FA Cup. This means that unless Rangnick inspires the club to an unexpected UEFA Champions League success, which would require them getting past Atletico Madrid in the round of 16, Manchester United will end the season trophyless for the fifth straight year.

However, in all fairness to Ronaldo, arguably the most self-demanding player the beautiful game has ever seen, he does not lay all the blame at Man United's door. In fact, the report claims that he has admitted to close friends that he is finally feeling his age.

Cristiano has aged like fine wine, that is undeniable. However, having just turned 37, the former Blancos superstar was bound to face struggles in such a demanding league and under a manager who wishes to employ high-intensity football. The goals have somewhat dried up as well, as he has failed to find the back of the net in five consecutive outings, his worst goal drought in 12 years.

Nonetheless, CR7 is keen to impress the interim German boss and has even installed an oxygen chamber at his house in order to recover better. It will be interesting to see how things end for the Portuguese legend.