All the action from the Etihad Stadium as Manchester City took on Porto.
18.50: We're at the end of the game. Not a classic performance by City, by any means, but they knew where the goal was when it mattered.
Aguero was exceptional, while substitutes Dzeko and Pizarro made a massive difference after coming on.
Porto go home after missing far too many chance. Hulk, in particular, flattered to deceive and has the potential to be some wealthy owner's biggest waste of money.
Thanks for keeping up, City safely through...
18.49: 'Man City have scored four goals in a European match (exc. qualifiers) for the first time since 1978 (4-0 vs Standard Liege).' Thanks Opta.
18.45: Manchester City 4-0 Porto. City ping the ball around the Porto box and Pizarro, only on the field for five minutes and with one assist to his name, shoots home on his debut to make it 4-0 on the night.
Scarcely deserved, given City's relaxed approach to the match after Aguero's opener and all of Porto's missed chances, but there's no doubting the Premier League leaders' attacking prowess.
18.41: Manchester City 3-0 Porto. Pizarro exchanges passes with Dzeko, gets to the touchline and crosses for Silva to tap in City's third. Very well worked goal.
18.41: In all the hoopla, I forgot the following - Rolando has been sent-off for a second yellow card for dissent in the aftermath of the goal. Bad, bad night for Porto.
18.39: Aguero - City's best player tonight - is replaced by David Pizarro.
18.36: Manchester City 2-0 Porto. No sooner do we take the p**s out of the big Bosnian, than he scores City's second of the night, and fourth of the tie.
Aguero steals into the box and sees off the weak challenge of Rolando, before rolling the perfect pass into the path of Dzeko. The substitute can't miss, and doesn't. That is that. Porto need four in 11 minutes.
18.32: A promising City attack is thwarted by ace Porto defender Dzeko, who we used to think was a striker in the Premier League. That pass was disgusting.
18.28: Hulk is reportedly worth something like €180bn. I don't see it. He's just a big lump.
18.25: Yaya Toure is booked for a foul on Moutinho, Hulk failing with the free-kick. Edin Dzeko is coming on for City, replacing Nasri. The game has drifted into tedium.
18.22: Lengthy treatment for an eye injury to Otamendi, who can eventually make his way off the field. Christian Rodriguez is on. Otamendi got a boot from his own team-mate, Maicon.
18.15: Porto have a goal from James Rodriguez ruled out for offside - it was clearly offside after some good build-up play - while I was being a bit premature about Richards. He's back on the pitch and Milner has replaced Barry.
18.13: Micah Richards is down and it doesn't look great. He buckled after launching a long ball upfield, with nobody near him. They're never good. James Milner will replace him.
18.10: Lucho Gonzalez shoots just wide of Hart's post. The veteran has been used sparingly in the Portuguese League of late, but he has impressed alongside Moutinho tonight.
18.06: How did City not score that? Aguero hassles the Porto defence into losing possession and he finds Silva. However, just as the Spaniard shoots, Maicon gets his interception in.
18.04: We're back in action, with City attacking from right to left. Aguero and Silva team up, the latter winning a corner for the home side.
Nasri floats the ball in but the referee stops play for a foul on Helton.
Half-Time: Sergio Aguero's gift of a goal is the difference on the night, and City lead 3-1 on aggregate. Porto have had four or five great chances, though, while Aguero and Yaya Toure should have extended their side's lead.
17.43: Gareth Barry concedes a foul outside his own box and Hulk lashes the free-kick wide, via a deflection. From the corner, Otamendi shoots over. He snathced at it. That was poor.
17.40: A Silva corner causes problems in the Porto box, but the visitors clear. City are clearly resting on their lead.
A better move follows as Aguero and Toure bear down on the Porto goal. Ultimately the Argentine blazes over when he should really have got his shot on target.
The atmosphere at the ground is muted.
17.37: Hulk does well on the left and his ball finds Fernando, who shoots over. Porto then go on the attack again with Lucho Gonzalez missing the target.
17.29: Wow! Silva plays the ball forward and Helton, inexplicably, comes out of his goal to fill the gap left by his right-back. Aguero seizes on the pass and lobs the Porto 'keeper from near the angle of the penalty area, but it hits the bar. Would have been some goal.
17.28: Porto have a free-kick in a dangerous position. Moutinho strikes it well but it's a fraction too high and Joe Hart isn't troubled.
The match has fizzled. Needs more Mario!
17.22: Porto are dominating possession but they're having trouble breaching the City defence. Hopefully City won't sit back, knowing Porto must score three times to win the game.
17.16: Very poor decision making from Toure and Nasri. The Ivorian advanced on the Porto goal and Helton came flying out of the box. Toure kept possession and passed to Nasri when he should have shot.
Nasri, in turn, passed back to Toure when he could have shot.
Toure blazed over. Chance wasted.
17.12: Yaya Toure. Man or machine? He's everywhere, not giving the Porto midfield a second on the ball.
17.09: That goal rattled Porto and it's been all City since. Samir Nasri had to be treated for a knock but he's up and running again. The Portuguese side can't get near Joe Hart.
17.02: Manchester City 1-0 Porto. Sergio Aguero scores for City twenty seconds into the match - surely one of the quickest European goals ever scored? Nigel de Jong pressures the Porto defence and the ball breaks to Yaya Toure.
The Ivorian slides in Aguero and the former Atletico Madrid striker does the rest, rifling past Helton in the Porto goal.
16.50: Here are the teams for this evening's clash:
Man City: Hart, Richards, Kompany, Lescott, Clichy, Barry, De Jong, Silva, Toure Yaya, Nasri, Aguero
Subs: Pantilimon, Zabaleta, Milner, Pizarro, Dzeko, Savic, Balotelli
FC Porto: Helton, Alex Sandro, Rolando, Otamendi, Maicon, Gonzalez, Fernando, Joao Moutinho, Varela, Hulk, James Rodriguez
Subs: Bracali, Cristian Rodriguez, Kleber, Djalma, Sapunaru, Defour, Podstawski