Manchester City defender Nathan Ake struck in the second half to earn a hard-fought 1-0 victory over visitors Arsenal in the FA Cup fourth round on Friday.
The top two teams in the Premier League cancelled each other out in the first half, with Erling Haaland twice going close for City while pacesetters Arsenal forced home goalkeeper Stefan Ortega into two fine saves to keep them at bay.
City's Pep Guardiola brought Julian Alvarez off the bench early in the second half, with the Argentina striker playing a big part in the winner, firing against the post before Ake slotted home from the follow up in the 64th minute.
Arsenal's coach Mikel Arteta rang the changes in search of a leveller but they could not break City's resistance as the hosts progressed and remain in the hunt to win the domestic trophy Guardiola has claimed just once during his time in England.
"Tight game, second half was better," Guardiola told ITV Sport. "Really difficult opponent.
"There is not one person in the locker room that is not very happy for him (Ake). We are happy for the goal and how he controlled one of the most dangerous players in the Premier League now in (Bukayo) Saka.
"As a manager you want players like Nathan. He deserves all the good things in life."
Despite making six changes to the side that beat Manchester United last weekend, with a first Premier League title in almost 20 years in sight, Arsenal started the brightest at the Etihad.
January signing Leandro Trossard from Brighton & Hove Albion looked lively, setting up an early opening for Takehiro Tomiyasu, who was denied by Ortega.
Haaland, eyeing his 32nd goal in all competitions in a remarkable debut season in England, was feeding off scraps, but all he needs is a half chance and the striker used his pace to capitalise on two Arsenal errors but was unable to find the net.
Kevin De Bruyne curled a shot wide, but it was Trossard who went closest to breaking the deadlock in the opening period, bringing a fine one-handed stop from Ortega.
City upped the ante after the break, finally wearing Arsenal down as Dutch defender Ake showed the finishing skills of a striker when calmly finding the bottom corner after Alvarez's effort had thundered against the upright.
With their main attention clearly elsewhere, Arsenal did not offer enough to find an equaliser. With the Premier League the priority, fewer games in a congested season could benefit the London side's quest for the big prize.
"I think we could have got much more out of the game," said Arteta, who was Guardiola's assistant at City before taking the Arsenal job. "One action changed it all.
"It is really difficult to win against this team but we went head to head with them. In the big moments, in big matches you have to make the difference. That is how you win these games."