Bristol City went toe-to-toe with Manchester City at the Etihad, but Aguero's late goal has the Premier League favorites in position to reach the League Cup final.
Manchester City nicked a late 2-1 win over Bristol City on Tuesday evening at the Etihad in what was an exhilarating Carabao Cup semifinal first leg.
The Robins went 1-0 up with a late first-half Bobby Reid penalty but a great team goal finished off by Kevin De Bruyne set the tie up perfectly for substitute Sergio Aguero to come off the bench and score a late winner.
Pep Guardiola didn't take the opposition lightly and went for a close to full strength side. Claudio Bravo was between the sticks, Oleksandr Zinchenko and Danilo filled in at full back while City veteran Yaya Toure got a rare game in midfield and Bernardo Silva, Leroy Sane and Raheem Sterling started in an interchangeable front three.
Bristol City had beaten four Premier League sides in a row in this competition before tonight's fixture, most notably the Sky Blues city rivals Manchester United in the last round, and they went all out at the Etihad.
Robins manager Lee Johnson reverted back to his favored starting XI after rotating for the 3-0 loss to Watford in the FA Cup on the weekend, but opted for Frank Fielding in net and new signing Liam Walsh on the bench.
Bernardo Silva almost opened the scoring in the 15th minute as he cut inside onto his favored left foot and cannoned his shot off a Bristol City defender's leg but unfortunately for the Portuguese winger, the ball looped just the wrong side of Frank Fielding's post.
Bristol City immediately raced down the other end of the pitch through marauding left-midfielder Joe Bryan but he could not repeat his exploits against Manchester United as Bravo was equal to his effort.
De Bruyne almost caught Fielding out with a cross early on in the game and tried to catch him out again in the 25th minute from a similar angle but the goalkeeper was able to punch the Belgian's near-post drive over the crossbar.
Bristol City were not going to roll over and succumb to arguably the best team in the world. They kept attacking and Marlon Pack popped up on the edge of the box to hit a clean volley but it was straight at Bravo luckily for the Chilean.
A series of defensive errors resulted in Bristol City getting a penalty late into the first-half. Eliaquim Mangala sloppily gave the ball away to Josh Brownhill, who poked the ball through to Bobby Reid and John Stones came sliding through him to give Anthony Taylor one of the easiest decisions he'll have to make this season.
Reid stepped up and despite Bravo's fingertips, managed to powerfully place the ball into the bottom left-hand corner to send the traveling support into raptures.
Man City almost instantly replied with a quick break but Aden Flint did fantastically well to launch all 6-foot-5 of him up to the height of the crossbar and head Sterling's chip over.
The first-half was a fantastic advertisement for why English cup football is still so special and the second 45 minutes started in the same manner. Flint towered over the Manchester City defense from a corner but couldn't get the required contact. City then immediately countered and Sterling rifled the ball at Fielding, who deflected the ball unconventionally away off his shoulder.
A beautiful goal from back to front in the 55th minute epitomized Guardiola's City this season. Bravo craftily picked out De Bruyne in what was the only pass on, who then drove towards the edge of the box, played a one two with Sterling and powered the ball into the back of the net.
Cracks were starting to show in The Robins' defense as Man City continued to wear them down with wave after wave of attack. Fielding had to save the day in the 69th minute when De Bruyne did well to reach the byline and square the ball to Sterling but the Bristol City goalkeeper miraculously kept the ball out.
De Bruyne is renowned for his outstanding technique but reverted back to the old fashioned toe punt with three minutes to go and it almost paid off but for a slight knick off a red shirt diverting the ball wide.
The Robins played fantastically all game but were crushed in stoppage time as Aguero, who had entered as a substitute, nicked in front of Fielding to head in Bernardo Silva's teasing cross. The Bristol City players looked deflated at the sound of the final whistle after giving their all, but can hold their heads high in defeat and will go again in the second leg at Ashton Gate in two weeks.