City's attack is strong enough to bail out their woeful defence

Manchester City made the semi-finals of the competition last-year and Sergio Aguero's second goal at the Etihad Stadium tonight was the club's 200th in European competition.

But, before this match, there remained a suspicion that this frustratingly inconsistent side lacked the necessary strength of character for the big European nights, especially with their persistently fragile defence.

There's no doubt that the defence remains a problem – and seeing 22-year-old John Stones comprehensively out-paced by 31-year-old Radamel Falcao will be especially concerning to Pep Guardiola – but this win over a clearly talented Monaco side could be the result to inspire a memorable European campaign for City.

Certainly it proved that their irresistible attack possesses enough quality to atone for that gaffe-prone defence. And that is no mean feat.

All of City's attacking players excelled and, at 3-2 down to a then rampant Monaco and with Caballero struggling, they still managed to rouse themselves to turn around the score. It was a stunning performance and a potential coming of age for Pep Guardiola's Manchester City.

If their forwards can maintain this kind of form, they can pose a threat to any of the teams left in this competition. Providing that their defence haven't already cost them the game.

Guardiola was right: Radamel Falcao is a killer

Against City Falcao banished memories of his struggles in the Premier League (Getty)

Pep Guardiola was emphatic in his praise of Radamel Falcao ahead of the Colombian's return to Manchester. “In the box, Falcao is a killer,” Guardiola said in his pre-match press conference. “He is a good professional, a nice guy and I am happy he is back at his level scoring goals."

Guardiola went on to describe how Monaco’s 4-4-2 formation, reminiscent of Leicester City last season, suited Falcao to a tee. Because “they attack inside and cross a lot – it’s perfect for him.”

It would appear Guardiola knows his football. Falcao proved a constant handful for Manchester City, with Monaco's highly impressive wingers repeatedly swinging in crosses for their front-man at every opportunity.

His first-half goal was superb and evidenced everything Falcao lacked during his two seasons in the Premier League: hunger, confidence, composure. Forcing himself in between City's defensive pairing of Stones and Otamendi, Falcao threw himself onto Fabinho's cross and powered a diving header past the hapless Caballero. It was Falcao's 14th goal in 15 games and one of his most important.

He would go on to miss a penalty at the start of the second-half but made almost instant amends, putting Monaco 3-2 up with a sublime chip over an onrushing Caballero. He was superb and desperately unlucky to find himself on the losing side.

Leroy Sane is fast becoming one of City's most influential players

Sane was superb playing on the left-wing (Getty)

This wasn't meant to be Leroy Sane's season. Not yet, anyway.

Signed from Schalke 04 for an eye-watering £37m, Guardiola insisted at the start of the season that – despite his high price – Sane was a signing for the future, a player who we should not expect too much from his first season in the Premier League.

But such is Sane's quality that Guardiola is finding it difficult to leave him out of his starting XI.

He played an essential part in City's opening goal: dancing around two defenders, he exchanged cute passes with Silva before firing the ball into the path of Raheem Sterling for a simple tap-in. He was always lively down the wing and was on hand to score City's vital fifth, which could well decide this tie.

Sterling also deserves much credit for a similarly exuberant performance down the right. On a night when City's defence toiled and their midfield was frequently overrun, they have their wingers – not to mention a superb performance from Sergio Aguero who scored a brace – to thank for winning them this tie.

Fabinho is more than ready for a move to the Premier League

Brazilian defender Fabinho has excelled for Monaco this season (AFP/Getty Images)

“The Premier League is a league that interests me and maybe one day I will come and play here,” Fabinho said with a smile and a wink ahead of this evening’s Champions League match, firmly placing himself in the shop window ahead of the summer transfer window.

The 23-year-old is wanted by both Manchester United and City – and it’s not hard to see why. He assisted both of Monaco's first-half goals and was a nuisance throughout, controlling the tempo from the middle of the park and repeatedly breaking down the right-hand side.

Other supposed Premier League targets also impressed. Kylian Mbappé was lively playing just off Falcao and his confident strike which gave Monaco the lead was remarkable for an 18-year-old. Thomas Lemar enjoyed a similarly impressive first-half before fading.

Monaco supporters will be distraught at how this match slipped from their grasp, but they should take solace in how prodigiously gifted their young team is. The real battle will be keeping their talented young stars out of the clutches of the bigger European teams.

City need a new goalkeeper. And fast...

Caballero struggled against Monaco (Getty)

Willy Caballero deserves an awful lot of credit for saving Radamel Falcao's second-half penalty; had the striker have scored, the outcome of this match could have been very different indeed.

But his performance was still lacking, especially at this level. He does not inspire confidence among City's back-line and is not a sufficient upgrade on the error-prone Claudio Bravo.

It is ultimately no surprise that City will not renew his contract at the end of the season.

His worst moment came in the first-half, as he attempted an ambitious pass to Fernandinho out on the left. But he failed to get enough power on the diagonal, with Fabinho gratefully intercepting before swinging in an inch-perfect pass to an onrushing Falcao.