Jose Mourinho insists Anthony Martial injured and tips Michael Carrick to be future Manchester United assistant

Manchester United 1-0 Watford: Marcus Rashford scores as Mourinho's side ended the Premier League season on a high ahead of next weekend's FA Cup final

Michael Carrick brought down the curtain on his illustrious playing career with a precise and lethal reminder of his passing ability although it was a potential farewell to his team mate Anthony Martial that threatened to dominate the final day of the Old Trafford campaign.

The French winger was expected to play against Watford in an attempt to convince his manager Jose Mourinho that he is worth some role in next weekend’s FA Cup Final with Chelsea, United’s last hope of silverware this season.

But, having arrived at the ground at noon, Martial reportedly immediately turned around and left, a move which the club’s in-house television station claimed was due to the French international being injured but one which raised more questions than it answered.

With Martial limited to 18 league starts this season, the latest development in his increasingly tense relationship with the United manager simply added to the theory that he may not be around when the club returns for next season.

Michael Carrick is given a guard of honour (Man Utd via Getty Images)

“It’s not true, he’s injured,” inisisted Mourinho after the match. “He was injured in the Friday training session, yesterday he couldn’t train. He had treatment in the morning at the training ground and he stayed away.

“I don’t know if he will be fit for the final. I know Romelu Lukaku will be back for Tuesday and we have to see but Anthony, I have no more.”

The same is certainly true of Mourinho’s loyal lieutenant Rui Faria, his right-hand man for 17 years but a coach who, United announced over the weekend, will leave the club this summer to try his luck in the managerial ranks.

All of which, neatly, brought attention back to Carrick, the 36-year-old midfielder who retired from football following his role in the victory over Watford and who will join Mourinho’s coaching staff next season.

Awarded a guard of honour by both teams before kick-off, and handed a first start of the season and made captain for the day by Mourinho, Carrick took 34 minutes to produce a memorable reminder of his magnificent passing ability.

Collecting the ball just inside his own half, the former England international lofted a pinpoint pass that floated fully 50 yards onto the toes of Juan Mata, behind the Watford defence.

The Spaniard selflessly and intelligently passed the ball square, and slightly behind, to the on-rushing Marcus Rashford who rolled the ball into the open goal. How United will miss that passing prowess and how they could have benefitted from it this season as they toiled, on so many frustrating occasions, to break down opposition defences.

It is precisely that sort of ability that helped Carrick amass an astonishing array of awards in his dozen years at Old Trafford – five Premier League titles, three League Cups, an FA Cup, each of the two major European trophies.

His style was often under-stated, and just as often under-appreciated, but not many players of the Premier League era have been able to influence a game as much as Carrick on the back of his passing and use of the ball.

On Carrick eventually stepping up as number two to replace the departing Rui Faria, Mourinho said: “I will organise my coaching staff in a way where the assistant manager figure doesn't exist. I am going to have assistant coaches and the reason is that I think it will be Michael Carrick in the future when he has his badges, his pro license.

“When he makes the bridge between a player to an assistant because people think it’s just like, one day I'm a player and the next day I'm a coach! It’s not like that. The brain can be like that but I don't think it makes sense when Rui is leaving after 17 years.

“I have nobody in the world of football ready to be my assistant manager so I prefer to educate people, to structure my staff in a way for when Michael has the pro license badges.”

And at least the tributes to Carrick, and speculation over Martial, offered intrigue on a day in which there was little riding on the on-field events.

Mourinho made wholesale changes, with an eye on the FA Cup final, and one of the stand-ins, goalkeeper Sergio Romero, made good use of his opportunity with an excellent first half save that preserved United’s lead.

Daryl Janmaat picked out the unmarked Richarlison with a magnificent cross from the right and his downward header looked destined for the back of the United net until Romero made a stunning dive to turn it away.

From the resulting corner, Gerard Deulofeu was handed another opening, this time steering a shot directly at Romero, as Watford pressed for the equaliser which their first half play would have merited.

Michael Carrick waves to the United supporters (Getty)

The second half offered even less in terms of goalmouth action, with Mata just failing to connect with Alexis Sanchez’s far-post cross and Marcos Rojo almost gifting the ball to Will Hughes in a dangerous position.

But the lack of on-field drama at least allowed United supporters to remember former Sir Alex Ferguson, currently recuperating following brain surgery, with a standing ovation for him midway through the second half.

After a weak Abdoulaye Doucoure header was comfortably gathered by Romero, there was time for Mourinho to allow Carrick one last accolade, taking him off six minutes from time to a rousing standing ovation, from both sets of supporters.