Romelu Lukaku has attracted much of the criticism for Manchester United's recent sub-par performances, but with Zlatan Ibrahimovic still sidelined, Jose Mourinho has little option but to defend his “untouchable” striker and persist playing him.

The Portuguese has other fires to fight in any case and the most urgent may be located directly behind Lukaku, where the decline of United's creator-in-chief needs to be quickly arrested.

Take a glance at the basic raw numbers and it is hard to deny that Henrikh Mkhitaryan enjoyed an excellent start to the season. The playmaker registered five assists in his opening three league games, each of which was an authoritative United win that promised much for the season ahead.

Mkhitaryan was more than meeting his quotas back then, even if some of the assists had more to do with the scorer’s finishing than his own vision and passing. When the final of the five came, a deflected corner that Marcus Rashford volleyed home against Leicester City, the Armenian's productive start all seemed a little unsustainable. Indeed, so it was.

Chelsea vs Manchester United: Player ratings Show all 23 1 /23 Chelsea vs Manchester United: Player ratings Chelsea vs Manchester United: Player ratings Chelsea vs Manchester United: Player ratings We run the rule over the two teams at Stamford Bridge. AFP/Getty Images Chelsea vs Manchester United: Player ratings Thibaut Courtois - 7 out of 10 Wasn’t overly tested but denied Lukaku in the first half and Fellaini at the death. AFP Chelsea vs Manchester United: Player ratings Cesar Azpilicueta - 8 Got the assist for Morata’s goal with a magnificent cross. AFP/Getty Images Chelsea vs Manchester United: Player ratings Andreas Christensen - 7 Repaid his manager’s faith in him after Antonio Conte named him in the starting XI ahead of David Luiz. Getty Images Chelsea vs Manchester United: Player ratings Gary Cahill - 7 Marshalled Lukaku and Rashford well alongside Azpilicueta and Christensen Chelsea FC via Getty Images Chelsea vs Manchester United: Player ratings N'Golo Kante - 7 Chelsea have missed his energy dearly. This was a solid comeback performance. AFP/Getty Images Chelsea vs Manchester United: Player ratings Davide Zappacosta - 6 Solid down the right but was replaced by Antonio Rudiger when United made a couple of attacking changes. Getty Images Chelsea vs Manchester United: Player ratings Cesc Fabregas - 9 The best player on the pitch by a country mile. Controlled the game and, as always, his passing was magnificent. Getty Images Chelsea vs Manchester United: Player ratings Tiemoue Bakayoko - 8 Magnificent in the heart of midfield but lacked quality when he strayed into more advanced areas. AFP/Getty Images Chelsea vs Manchester United: Player ratings Marcos Alonso - 7 Showed close to the form he was in last season as he got up and down the left wing all game. AFP/Getty Images Chelsea vs Manchester United: Player ratings Alvaro Morata - 8 Planted a sumptuous header beyond De Gea to give Chelsea the lead. Chelsea FC via Getty Images Chelsea vs Manchester United: Player ratings Eden Hazard - 8 Always seems to turn it on when it matters. Stung De Gea’s palms with a fierce first-half drive and, as we’ve come to expect, was one of Chelsea’s most dangerous players. Getty Images Chelsea vs Manchester United: Player ratings David De Gea - 7 Made a few good saves to keep United in it but could do nothing about Morata’s winning goal. Getty Images Chelsea vs Manchester United: Player ratings Eric Bailly - 6 An erratic performance by a player who usually defends so well for United. AFP/Getty Images Chelsea vs Manchester United: Player ratings Chris Smalling - 7 Probably United’s best player on the day after being left out of Gareth Southgate’s England squad. Getty Images Chelsea vs Manchester United: Player ratings Phil Jones - 5 Put the ball into his own net early on only to be bailed out by the referee, who deemed Morata to have fouled him. Getty Images Chelsea vs Manchester United: Player ratings Antonio Valencia - 6 Solid at the back but looked to be struggling with injury towards the end of the match. Getty Images Chelsea vs Manchester United: Player ratings Ander Herrera - 5 Combative but lacks the creativity that the injured Paul Pogba possesses. Was part of a United midfield that just couldn’t link defence and attack. Man Utd via Getty Images Chelsea vs Manchester United: Player ratings Nemanja Matic - 6 One of United’s better performers on the day but was outshone by Tiemoue Bakayoko, the man who replaced him at Stamford Bridge in the summer. Getty Images Chelsea vs Manchester United: Player ratings Ashley Young - 5 Should’ve claimed an assist for the game’s opening goal but Rashford headed his cross over the bar. Quiet otherwise. Getty Images Chelsea vs Manchester United: Player ratings Henrikh Mkhitaryan - 3 The game passed him by. He’s in poor form at the moment after a superb start to the season. Getty Images Chelsea vs Manchester United: Player ratings Romelu Lukaku - 6 Delivered an energetic performance against his former employers and was denied the game’s opening goal by a good Thibaut Courtois save. Faded after the break. AFP/Getty Images Chelsea vs Manchester United: Player ratings Marcus Rashford - 5 Had a superb headed opportunity in the first half but appeared to back out slightly with Courtois charging towards him and ended up missing the target. Getty Images

His personal numbers since those first three games do not make for pleasant reading. Mkhitaryan has failed to set up one of his team-mates in the league since August and he has scored just once all season, notching with a late finish against an Everton side ready to throw in the towel. A single strike and a single assist on the Champions League trip to CSKA Moscow is all he has managed in other competitions too.

It is, all told, seven games since his last goal or assist. Rather than playing ‘in the hole’, Mkhitaryan seems to have fallen down one and United have suffered as a result.

Incredibly, since the start of September, Mourinho’s side have created less than Stoke City, Crystal Palace and Bournemouth, three clubs experiencing difficulties at the wrong end of the table. Who are the Premier League's five most inventive teams in the same period? United’s direct title and top-four rivals, of course. Is it any wonder then that the displays against Liverpool, Tottenham Hotspur and Chelsea were poor on the whole, even if the results were mixed?



​Mkhitaryan has to take a portion of the blame for these recent struggles and if the Armenian’s time on the pitch is anything to go by, Mourinho has realised as much. The Armenian has been substituted in all 10 of his league starts this season and he is gradually being taken off earlier and earlier. Whereas at the beginning of the campaign he was only withdrawn after the 80-minute mark, Mkhitaryan is now trusted for little more than an hour.

The nadir of his season so far came at Stamford Bridge on Sunday when he was replaced after 62 minutes. He could have no complaints. While Cesc Fabregas, operating alongside Eden Hazard and behind Alvaro Morata, laid on six chances for Chelsea that afternoon, Mkhitaryan could not manage one. Marouane Fellaini, his replacement, fashioned two despite being on the pitch for the half the time.

It seems the right moment to pull Mkhitaryan out of the firing line and hope the rest will help him rediscover some form. A dose of tough love certainly appeared to help last season, when his full integration into life at Old Trafford was postponed until November.

Yet if he is to drop out of the side, who should replace him? Juan Mata, the natural choice, is quietly getting away with an even less productive season. The Spaniard has scored just once and is yet to assist. Jesse Lingard could fill in but his audition during the defeat to Huddersfield Town was hardly convincing. None of the other options are a natural fit: injuries mean Ander Herrera is better deeper and needed there, Fellaini is more of a ‘Plan B’, Paul Pogba remains out and is more effective in a midfield pair.

Therein lies the rub. In Mkhitaryan, Mourinho has a second out-of-sorts player who still has to start week in and week out despite his slump in form. There are too few alternatives in United's squad and ultimately, none of them can compete with the invention of a player who is capable of racking up 32 assists in a single season.