Aguero doubled City's lead with a brilliant low strike from 25 yards that fizzed past Ben Foster and into the bottom corner.
West Brom put the brakes on City's fast start with a well taken goal on the break by Graham Dorrans, who shifted the ball onto his left foot and finished clinically.
City re-estabished their two-goal cushion in the 36th minute, when another Argentine found the net. Martin Demichelis lost his marker in the box and tapped in after Vincent Kompany had flicked on the corner.
The second half was a less eventful affair as City closed out a win that keeps West Brom only three points clear of the relegation zone. But there will be significant concern over the next few days over Silva, whose ankle injury will be a worry to City and Spain.
3' - GOAL! Manchester City 1-0 WBA. Zabaleta's header beats Foster after the keeper parried Aguero's effort.
9' - GOAL! Manchester City 2-0 WBA. City two up after a thunderbolt by Aguero who drills an unstoppable low drive into the bottom corner from 25 yards.
16' - GOAL! Manchester City 2-1 WBA. West Brom back in it as Silva & Fernandinho's misunderstanding at a free-kick allows West Brom to break. They do just that and tear City apart on the counter-attack, with Dorrans's quick finish beating Hart.
36' - GOAL! Manchester City 3-1 WBA. City re-establish their two-goal advantage through Demichelis, who taps in at the far post.
42' - Sessegnon chance! Jones's cross finds Sessegnon, whose first time shot is heading in, but Kompany makes a vital block on the slide to send the ball looping onto the roof of the net.
81' - Good save by Hart! Berahino flicks on a cross from the left and the England goalkeeper makes a very good reaction stop to keep City two goals ahead.
City have scored four goals in the opening three minutes of games this season - more than any other Premier League team.
Sergio Aguero has now scored four goals in his five Premier League games against West Brom.
West Brom have taken just two points from their last seven Premier League games at the Etihad Stadium (D2 L5).
Can Manchester City still win the league? It's a tall order, but they're keeping themselves in it and are still scoring plenty of goals, which could be vital come the end of the season. If City do somehow win the title, it will almost certainly be on goal difference.
MAN OF THE MATCH
David Silva (Manchester City) - Stitched everything together for City and was at the heart of everything that they created. But there will be concerns over whether he'll feature again in the Premier League this season - or at the World Cup - after a serious looking ankle injury.
Manchester City: Hart 7, Zabaleta 7, Clichy 7, Demichelis 8, Kompany 8, Fernandinho 7, Javi Garcia 7, Nasri 7, Silva 8, Aguero 8, Dzeko 7. Subs: Jovetic 6, Milner 6, Kolarov N/A.
West Brom: Foster 7, Jones 7, Dawson 6, Olsson 6, Ridgwell 5, Mulumbu 7, Brunt 5, Amalfitano 7, Sessegnon 7, Dorrans 8, Vydra 6. Subs: Anichebe 7, Berahino 7, Morrison N/A.
MATCH IN A TWEET
- Sports & Recreation
- Manchester City
- David Silva
- Sergio Aguero
- Pablo Zabaleta