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Chris Smalling was so inept in the defensive third at Newcastle that Jose Mourinho told him to switch ends for the finale. As Marouane Fellaini nurses his knee following surgery, Mourinho remains intent on the tall figurehead, be it Smalling, Romelu Lukaku or Scott McTominay, who was United's final substitution at St James' Park.

Luke Shaw was also warming up but may as well have remained seated. Mourinho is a stickler for tall players and McTominay, a tidy if timid player on the ball, would maybe not have earned a first-team squad promotion had he not grown 10 inches in 18 months.

United supporters were barely audible amid the Geordie cacophony following Matt Ritchie's strike and it would be difficult to register the sighs from their bird's eye view way up in the Laezes Stand. Sigh they must have, though, as Mourinho again depended on a big man to salvage another game. Smalling went up front at Huddersfield when Fellaini was unavailable, the Belgian almost earned United a draw at Chelsea and was needed at Tottenham until he succumbed to injury. Zlatan Ibrahimovic was the first to emerge in the December derby defeat.

Bringing Shaw on would have shown more adventure. Ashley Young, one of the more commendable performers on Tyneside, could have headed further up the left wing to accommodate the attack-minded Shaw, moving Anthony Martial into the striker's role, thus enabling three players to play in their favoured roles. Instead, United reverted to desperation and what used to be their greatest strength has become one of their greatest weaknesses; they have won four matches from losing positions during the Mourinho era.

Before the warm weather training trip to Dubai last month, Mourinho said United would 'work on some tactical details I think would be good for the second part of the season'. Those details must have evaporated in the Middle Eastern heat. United's set-up has never looked as rigid under Mourinho and the 4-2-3-1 formation which was moot in the opening months of the season has become so problematic Jonjo Shelvey outplayed Paul Pogba and Nemanja Matic.

United's two central midfielders were substituted and Mourinho indirectly bemoaned their defending for Newcastle's winner. The concern with a midfield axis has not gone unnoticed by the players, either. A source claims it was 'lively' in the dressing room during the interval against Huddersfield earlier this month, with reservations aired over Matic and McTominay's lateral passing. Pogba's decision-making in the dying embers of the narrow Burnley win last month was also questioned, although the Frenchman conceded he was wrong to shoot rather than pass after a United analyst provided him with the relevant footage.

Pogba ended his warm-up early at Newcastle and winced when journalists asked how he was in the St James' mixed zone. Injury did not contribute to Pogba's disappearing act at Spurs and it was surreal that Mourinho fielded the same XI at Newcastle. Those selection quirks could not legislate for Martial or Alexis Sanchez bottling one-on-ones with the game goalless but there are fundamental problems with what was considered to be United's best XI.

Smalling is at times unsteady with the ball at his feet and it makes a mockery of Mourinho's reliance on him and Phil Jones as the preferred partnership in Eric Bailly's absence.

That reflects particularly damningly on Victor Lindelof, a player ostensibly signed to enable United to operate with a back three and play the ball out of defence. Lindelof was jittery again on his last start at League Two relegation fodder Yeovil and Mourinho sought reassurances from his Portuguese contacts after just a month of coaching the Swede. The apparent lack of faith is so acute the 23-year-old has not played in the league since New Year's Day.

Marcos Rojo is another imperfect ball-playing centre-back but formed a reasonable rapport with Jones last term and was unfortunate to be dropped at Newcastle. United have conceded just three goals this calendar year and remarkably have the best defensive record in the league, yet could be tempted to make another addition at centre half and right-back is an emerging problem position. Valencia, at 32, has too heavy a workload and his hesitancy kills United's attacking flow.

There is a clamour to switch from a midfield two to a three. Manchester City usually play in a 4-3-3 but two of their trio just happen to be the best playmakers in the league and United lack the profile of Kevin de Bruyne or David Silva, a consequence of Mourinho's transfer policy and the emphasis on bulky six footers. That seems outdated.

United lack fluidity in attack and Newcastle effectively played against half a midfield at the weekend. Pogba seemed injured and Nemanja Matic is believed to have been carrying an injury since Christmas time. Mourinho refused to offset the restrictions by selecting McTominay or Michael Carrick on Sunday and Shelvey collected the man of the match award. A plucky academy graduate or a 36-year-old are not stellar options, though.

The 4-3-3 is not fool-proof. United had a midfield triumvirate at Stoke in September and drew before they lost at Basel and Bristol City. They have won two of their five with the system and one of the triumphs was at Football League side Yeovil. It should be inconsequential at relegation threatened Newcastle, provided two fit midfielders are starting.

United's 4-2-3-1 has become so fixed it has become apparent the best players do not make for the best side. Juan Mata's incision was missed until he came on at Newcastle and Jesse Lingard remains an instinctive asset still prone to drifting out of matches. By signing Sanchez, United have strengthened the wrong side and it remains doubtful they will enhance the right flank from within. The attacking balance is lopsided in contrast to City, who have eschewed the 'inverted' winger in favour of natural wide-men in Raheem Sterling and Leroy Sane.

Mourinho is approaching the most pivotal period of his second season with trips to Huddersfield and Sevilla prior to the visit of Chelsea within an eight-day period. United could kick-off that fixture behind Liverpool and end the matchweek in fourth but Antonio Conte elicited the outstanding performance from Mourinho's United 10 months ago. Zlatan Ibrahimovic and Henrikh Mkhitaryan were benched and the 3-5-2 formation flummoxed just about everyone. United won 2-0 and started with three midfielders.

And they did it without Smalling.

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