Arsenal boss Mikel Arteta made six changes against a virtually full-strength City side but was only undone by a second-half Nathan Ake strike.
Man City’s Nathan Ake celebrates after breaking the deadlock against Arsenal Credit: Reuters
The defender curled home after being teed up by Jack Grealish Credit: Getty
City had lost defender John Stones to injury moments earlier Credit: Getty
Eddie Nketiah and Arsenal failed to find a breakthrough against the Cityzens Credit: Reuters
This was the first meeting of the season between the Premier League leaders and the champions and it was a decent appetiser for the more serious battle at the Emirates on February 15.
City progressed to the fifth round but Arsenal proved they have greater squad depth than many reckoned.
It was not the worst outcome for Arteta. Had he selected his strongest side and suffered a beating, we’d be talking of psychological scars.
There was none of that after this encounter – Leandro Trossard, on his full debut, illuminated the first half and will add serious competition for places at the North London side, who lead City by five points with a game in hand.
The last time Arsenal visited this place, they were gubbed 5-0 early last season, with resounding calls for Arteta’s head.
How times have changed for Guardiola’s former right-hand man, who is now threatening to dethrone his old boss.
City, despite their dominance of the League, have only won one FA Cup in the last decade and Guardiola clearly has an appetite for another.
Beating the leaders cannot be bad for their confidence yet this was not exactly convincing.
For 64 minutes, it felt as if we were heading for a replay and a heavyweight trilogy between England’s best two sides in the space of 19 days.
Ake ended that idea with a cool finish after sub Julian Alvarez had crashed a shot against the post.
But Arsenal, closer to full strength after Arteta had made his subs, staged a serious spell of late pressure in an attempt to take City back to the Emirates next week.
When the teams were announced, it was clear where Arteta’s priorities lay – those six changes included the benching of skipper Martin Odegaard, Gabriel Martinelli and William Saliba.
Guardiola, clearly up for the Cup, changed only two of his starting line-up from last weekend’s victory over Wolves.
Arsenal have added depth with the signing of Trossard from Brighton.
The Belgian forward, on his first Gunners start, gave John Stones an early filleting and teed up Takehiro Tomiyasu for a rattling long-ranger which City’s stand-in keeper Stefan Ortega pushed away.
At the other end, Erling Haaland was giving Rob Holding a physical going-over.
And when City’s goal machine pounced on a mistake from his marker, keeper Matt Turner raced out of his area to block and the Norwegian attempted a saucy 25-yard bicycle kick, only for Tomiyasu to clear.
Trossard, having plenty of joy on the left flank, was soon rinsing Rico Lewis and drilling a shot which Ortega dived to fend away.
Mikel Arteta suffered defeat for the first time in nearly three months Credit: Reuters
De Bruyne got some serious bend on a shot which narrowly cleared the far post.
But for once, De Bruyne wasn’t even the liveliest Belgian on this pitch – Trossard continued to torment City’s defence and this time, he squared for Eddie Nketiah to shoot wide at the near post.
Despite all their changes, Arsenal were playing some excellent stuff, knocking it about with pace and purpose.
For City, though, there was always Haaland, who beat Gabriel and lobbed Turner only for his effort to land wide.
City were growing tetchy, with ref Paul Tierney and with one another, Guardiola was doing his conkers on the touchline, even out-Fawltying Arteta.
Stones limped off in first-half injury-time, after a heavy challenge from Trossard, and was replaced by Aymeric Laporte.
Holding had just been booked for rugby tackling Haaland, the Arsenal centre-back’s selection always looking like Arteta’s riskiest one.
And at half-time Holding was hooked in favour of Sailba, while Albert Sambi Lokonga replaced Thomas Partey.
Arteta and Guardiola still have to face off two teams in the Prem title race Credit: Getty
Guardiola soon turned to Kyle Walker and Julian Alvarez but the spark was beginning to go out of the contest, when – out of the blue – City scored.
Alvarez, the Argentinian World Cup winner, crashed a long-range shot against the foot of the post, Jack Grealish received the rebound, dribbled around Tomiyasu and laid back for Ake to guide his shot inside the far post.
Arsenal almost managed an immediate response, Granit Xhaka’s artful centre almost fell to Nketiah but Laporte nicked it off his toes in the six-yard box.
Arteta wasn’t going to lie down, though, and brought on former City man Oleksandr Zinchenko and Odegaard.
The visitors enjoyed plenty of late pressure but City, with Laporte to the fore and Ortega alert when he needed to be, held firm for a place in the last sixteen.
There will be better to come next months when these two meet at full strength and at full tilt for the title.
But for the blessed Arteta, even a rare defeat felt like a minor triumph.