Boro are happy to let City play for a spell now, as the home side look to rekindle their best. 

But Kevin de Bruyne makes the wrong decision in floating a header towards goal rather than across it, easily gathered by Victor Valdes.

Simon Stone
BBC Sport

If Alvaro Negredo had found the net with that audacious attempt at the start of the second half, it would have eclipsed any of the 23 he scored in his single season for Manchester City.

His last Premier League goal on this ground was pretty memorable though, given it was the winner against Liverpool on Boxing Day 2013.

Real signs of a threat.     

Adam Forshaw lays up a brilliantly weighted pass for Adama Traoare to chase - he beats Aleksandar Kolarov to it and wins a Boro corner.

But it's wasted as Calum Chambers is called offside chasing down a deflection when the corner's played short.

Bizarre how often this happens. Complacency creeping in? 

Manchester City are giving the ball away, committing silly fouls, and there could be a way back in for Boro if they keep this up you know. 

Alvaro Negredo is slipped in beyond enemy lines but the flag goes up as he lobs an effort over Claudio Bravo and wide.

Sounded like a smattering of appreciation from the home fans for their former striker there, along with the Boro voice.   

Tray Brown: Sergio Aguero has a better goals to game ratio in the Premier League than Thierry Henry. Class.

Alex Baloolal: Aguero fastest ever to 150 goals? And still never made a Premier League team of the year.

Image source, EPA

Chris Waddle
Ex-England winger, BBC Radio 5 live at Etihad Stadium

It's a different Middlesbrough that's come out in the second half. They're more ambitious and City have been a little sluggish.

Lovely skills from Adama Traore - he's looked really good today. Bamboozles Kevin de Bruyne for once as he turns calmly out of stormy waters. 

Adam Clayton then goes in the book for a very late challenge on David Silva. Terrible foul.

He's had nothing to do all game but Claudio Bravo has to save his side twice in as many minutes. 

Boro break after a sloppy John Stones pass and Bravo has to come racing out to smother at Adam Forshaw's feet. A fine stop - and it bounces off the Boro man for a goal kick, too. 

Definitely much more about this Boro set-up post-half-time you know. There is bite.

Image source, Reuters

Image source, Reuters

WHA?! This would have been goal of the decade!

Just inside his own half, Alvaro Negredo tries to lob Claudio Bravo - from downtown! 

Bravo is scrambling - for a moment we believe - but just gets back in time to tip over the bar. Definitely dipping in. 

Where on earth did that come from??

Image source, Getty Images

Will it be a landslide? Will Boro be shell-shocked after that first-half blitz? 

Early signs: George Friend munches through Pablo Zabaleta to win the ball and nutmegs his man to glide up the pitch. 

It doesn't last long though. All bets are on City soon slipping back into the Guardiola groove.

We are back under way!

Image source, Opta

He had to be beaten eventually.

Victor Valdes made six saves, a couple of them outstanding, but in the end he was beaten low to his left just before half-time.

Chris Waddle
Ex-England winger, BBC Radio 5 live at Etihad Stadium

Aitor Karanka has got Fischer, Nugent and Stuani on the bench if he wants to change it.

Some managers think that if they go for it, they'll get picked off again and again and they end up losing 4-0 or 5-0.

I can't see him changing it, but I can't see them scoring. They're not even getting any set-pieces.

Simon Stone
BBC Sport at the Etihad Stadium

Pep Guardiola enjoyed that goal.

The Manchester City manager did one fist-pump, pointed at Sergio Aguero, clapped expansively, then did another fist-pump for good measure.

I am not entirely certain what part of that he was particularly pleased with but given Middlesbrough have barely touched the ball in the City half, Sergio Aguero has just sealed victory for the home side unless there is a major shift in approach from the visitors.

Image source, Getty Images

On the basis of what we've seen so far, I can't see Boro getting back in it. 

Zero shots. City playing with their tails up. 

Jesus Navas crashes against the frame just before the half-time whistle. I think Victor Valdes had let that go because he thought it was going behind? Risky!

Chris Waddle
Ex-England winger, BBC Radio 5 live at Etihad Stadium

That's the type of ball you need - nice and early, it didn't allow Middlesbrough's defence to block the space off.

Aguero gambled and it's a good finish. He makes things look very easy. A quality cross and a quality finish.

Image source, Getty Images

TWO minutes added on. Time for another? When it rains it..?

Free-kick City on the edge of the Boro box. Antonio Barragan the guilty man for a block off the ball on Kevin de Bruyne.

David Silva takes. Headed clear by the away side again. 

Can they hang on until the break? Three minutes left...