What would the response have been if Liverpool had tried to sign a couple of Manchester City’s fringe players last summer? The smart money is on City refusing to sell. They surely would have regarded Liverpool as the likeliest threat to their hopes of retaining the Premier League title and seen no value in making it that easy for them to strengthen their squad. But it was different when Arsenal came calling for Gabriel Jesus and Oleksandr Zinchenko. Liverpool had pushed City to the limit, taking the title race to the final day. Arsenal had relinquished fourth place to Tottenham, finished 24 points below City and for all their youthful promise done little to suggest that they were ready to challenge at the top. In that context City could have been forgiven for failing to see Arsenal as a threat. They had given the champions a fright at the Emirates Stadium last season, but the game still ended in another City win. The impression was heightened: Arsenal could excite, they could compete in flashes, they could play sparkling football, but when it came to the crunch they still lacked the conviction and discipline required to beat the best. Not any more. Arsenal should not have an inferiority complex when they visit the Etihad Stadium in the fourth round of the FA Cup on Friday. They are five points above City at the top of the table, with a game in hand, and are the best team in England at the moment. “It’s been quite a big transformation,” Mikel Arteta said. “The team we had in the beginning to the team we have right now, it’s night and day.” It has been a case of clever team-building and it picked up pace with the arrivals of Jesus and Zinchenko. They were surplus to requirements at City, but have been outstanding for Arsenal. The environment has been perfect for Jesus, who was thriving as the main man in attack before being sidelined with a long-term knee injury, and has also brought out the best in Zinchenko. Who knew the Ukraine international was this good? At City, Zinchenko seemed a useful squad player; at Arsenal he is essential, catching the eye with his leadership and making Arteta’s football work by drifting in from left-back to link with Thomas Partey and Granit Xhaka in midfield. Zinchenko has made a huge difference. He played a key role in Eddie Nketiah’s winning goal against Manchester United last Sunday and his form has raised the inevitable question of whether City were guilty of complacency when they agreed to do business with Arsenal. What’s the worst that could happen? Well, it seems they have inadvertently created a monster. Liverpool weren’t the threat. It was Arsenal. No wonder Arteta was asked whether City would think twice before selling to them again. “I don’t know,” he said. “It was an agreement between three parties and we were all very comfortable with it. What could happen in the future – who knows?” One answer is that Arsenal could land a psychological blow by knocking City out of the Cup. It will be fascinating to see how Arteta plays it. Does he ignore talk of fatigue and go on the offensive? Or is this a moment to play a second string; for Arsenal to keep their powder dry before they host City in the league on 15 February? In all likelihood the selection will fall somewhere in between. Arteta spoke about maintaining momentum. He could give opportunities to Rob Holding, Takehiro Tomiyasu and Kieran Tierney in defence. He could protect Partey and have a look at Fábio Vieira. Leandro Trossard, newly arrived from Brighton, could start in attack. Arteta should not go overboard. This is a chance for Arsenal to underline their quality. A win would do wonders for their confidence, not least because they have to face City twice in the league. It was no surprise to hear Arteta talk so glowingly about Pep Guardiola. He was Guardiola’s No 2 at City and has been a fan since their days as players at Barcelona. Rivalry has not dented their friendship. “We are really different as people and we are very different as managers,” Arteta said. “That is why we understand each other so well and have the relationship that we have.” Arteta remembered how Guardiola inspired him as a midfielder. “We grew up in the same position,” he said. “I loved the way he played. He was an inspiration since I was 18 years old.” Now Arteta and Guardiola are on an equal footing. Boosted by Zinchenko and Jesus, Arsenal are on their way to replacing Liverpool as City’s main competition. This could be the start of a classic rivalry.