Anthony Martial threatened a late comeback from the spot but United looked devoid of options as they fell to defeat
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SERGIO AGUERO was the silver fox in the box as his second half strike helped City win the Manchester derby.
The club's all-time leading goalscorer had his hair dyed grey ready for the 177th meeting between these two old rivals.
But he still looked young and fresh as he linked up superbly with Riyad Mahrez to score the champions' second goal just after half time.
And it proved to be enough despite threatening yet another famous late comeback.
Just as they had in previous games against Southampton and Shakhtar Donetsk, City flew out of the blocks with Bernardo shooting inches wide in the first minute.
It seemed inevitable the intense pressure would eventually tell and the only surprise was that it took until the 12th minute.
A Raheem Sterling cross from the left was pulled back by Bernardo and Sergio Aguero went down under a challenge by Chris Smalling.
Referee Anthony Taylor played the advantage and Silva took full advantage - scoring with his right foot to score his seventh goal of the season.
United had just not got started and it's fair to say United had not got started - they had made only 11 passes and six of those had not found a man.
Credit to Jose Mourinho's men for weathering the early storm and hanging in there though - as they began to play their way back into the game.
A possible handball by Smalling in the box was not spotted by Taylor and the visitors went in at the break just one goal down.
Yet that changed within five minutes of the restart as Aguero played a neat one-two with Riyad Mahrez before hammering a shot past David de Gea.
After the Argentine's 11th goal of the season, Jose Mourinho knew he had to do something so threw on Romelu Lukaku for Jesse Lingard shortly before the hour mark.
And the Belgian made an immediate impact as he was upended by Ederson in the box and the ref pointed to the spot.
Anthony Martial sent Ederson the wrong way from the penalty and United were back in the game with more than half an hour remaining.
United famously turned round a two goal deficit to win here in April and that goal had City biting their nails once more.
The league leaders wasted good opportunities to extend their lead with Fernandinho and sub Leroy Sane both guilty.
Sterling held the ball up for Bernardo whose cross landed at the feet of sub Ilkay Gundogan who took a touch before scoring past De Gea.
