Alex Ferguson’s men were rarely at their best against a determined Birmingham outfit but the visitors never really looked like finding their way through a defence that has conceded just twice on home soil all season.

The beauty of Tevez’s 10th goal of the campaign, a neat finish after Cristiano Ronaldo had returned the Argentine’s overhead kick with a impish back-heel, was at odds with the fractured nature of the contest.

But, as Tevez also hit the post on two occasions, United were worthy of a 10th successive home win, even if the matchwinner’s dummy-sucking celebrations raised an eyebrow or two.

And, the sight of the already-substituted former West Ham man needing to be carried to the dressing room by two members of United’s backroom staff after the final whistle was not what Ferguson would have wanted.

Whether it was the new year festivities taking effect or just a belief that their team did not require any assistance to bounce back from Saturday’s shock defeat at West Ham, there was a distinct lack of support from the United fans.

At times, the stadium was completely quiet, a fact not missed by the Birmingham contingent.

For long periods, precious little happened on the pitch to lift flagging spirits either.

Wayne Rooney’s continued illness not only robs United of a key attacking force but also a man capable of bringing an entire crowd to its feet with one blockbusting surge or chase back to make a tackle.

Handed his first start since March, Park Ji-sung worked predictably hard, as did Nani on the left flank. But equally predictably, it was largely left to Ronaldo and Tevez to test Birmingham’s defence.

Tevez might have put the hosts ahead in the opening stages when he rose to meet Patrice Evra’s near-post cross. Instead, the South American powered his header against the foot of Maik Taylor’s right-hand post, meaning United were forced to endure another 20 minutes of frustration before they eventually made their breakthrough.

Birmingham might feel aggrieved that Michael Carrick opted to play on when Cameron Jerome failed to rise from an aerial duel with Rio Ferdinand.

However, under the letter of the law, the Red Devils were entitled to do just that and Jerome’s problem had little effect on what happened next as Carrick flicked the ball into Tevez’s path.

After finding Ronaldo with an overhead kick, Tevez continued his run, collecting an inspired back-heeled return pass inside the Birmingham box before beating Taylor in a manner that looked far easier than it actually was, before celebrating in bizarre fashion, pulling a dummy out of his pocket and sticking it in his mouth.

Ferguson, completing a two-match touchline ban, must have been dismayed at his side’s inability to capitalise on their advantage.

Had Gary McSheffrey showed a bit more calmness, he could easily have levelled with an angled drive, while Sebastian Larsson curled a free-kick straight at Tomasz Kuszczak in stoppage time.

Birmingham could only have gained more heart from surviving more United pressure at the start of the second period, when Tevez struck the post for a second time.

What the former Boca Juniors player lacks in size he more than makes up for in determination and after muscling his way on to Park’s pass, Tevez deserved more than to see his 10-yard effort cannon back off the woodwork.

It seemed Ronaldo would eventually turn home the rebound but McSheffrey threw himself in the way of the winger’s shot.

Taylor pawed the ball away from John O’Shea after he had spilled Tevez’s fierce near-post cross at the Irishman’s feet.

Tevez certainly deserved the standing ovation he received when he was replaced by Louis Saha 19 minutes from time but it must have been slightly frustrating his efforts had not wrapped up the points before his exit.

Birmingham promptly enjoyed their best spell of the game, with former Chelsea man Mikael Forssell causing some anxiety within home ranks when he drifted a low shot just wide.

Another Forssell volley followed but that too was off target and United’s only remaining problem was the late booking picked up by Wes Brown that will rule him out of the encounter with Newcastle on January 12.