Napoli boss Rafael Benitez has shown Arsenal's Premier League title rivals how to stretch the Gunners, says Jamie Redknapp.
Benitez's side secured a 2-0 win over Arsenal but could not stop the north Londoners scraping through to the Champions League last-16 on goal difference.
Goals from Gonzalo Higuain and Jose Callejon not only denied the Gunners a point but ensured that Borussia Dortmund's 2-1 win over Olympique Marseille was enough for the Germans to finish top of the group on goal difference.
Reflecting on Arsenal's defeat, Redknapp told Sky Sports: "I think you have to credit Rafael Benitez because he changed it a little bit tactically, certainly in the second half when he pushed the two full-backs Maggio and Armero high up the pitch.
"That forced Arsenal back and Rosicky and Cazorla then had to become more of a defensive unit. That change is where the goals came from. That made a big difference in the game because Napoli were a bit more passive in the first half but they really pushed onto Arsenal in the second and gave them so many problems.
"Higuain's goal came from a piece of brilliance. He set the ball off and then a little bit of movement created space and he takes three touches and crashes the ball into the corner. It was a fantastic piece of centre-forward play.
"Benitez started with Pandev but when he brought on Insigne (on 57 minutes) he changed the game. I'm pleased this little guy didn't play from the start, from Arsenal's point of view, because he can play the type of little passes that set up Callejon's goal. He's a talented young player and we'll see him in the World Cup for Italy."
Redknapp's fellow Sky Sports pundit Gary Neville, who won the 1999 Champions League with Man United, said that Napoli had highlighted a potential weakness in Arsenal's formation that Manchester City could exploit when the two sides meet at the Emirates on Saturday.
"I think there is a little pattern developing in Arsenal's last two games, against Everton and this one, where Cazorla has been driven back," agreed Neville.
"On Saturday against Manchester City the likes of Kolarov, Clichy and Zabaleta are going to fly forward and if Arsenal do play Wilshere and Cazorla they are going to end up deep and then they can't get back up the pitch.
"That means Giroud is isolated. I think it is a no-brainer to play Theo Walcott on Saturday. I thought they would have brought him on in the second half against Napoli because there was a little pattern there."
Arsenal's bid to get back into the game after Higuain's opener on 73 minutes was hindered three minutes later when Mikel Arteta was sent off after picking up his second yellow card.
But Neville said the midfielder had every right to feel aggrieved about the decision, saying: "I thought he was unlucky.
"He can have no complaints about the first yellow card but the second one was for a nothing challenge. You could argue that the referee has a decision to make because Arteta is a bit clumsy but that's all it is.
"It looks from the referee's angle potentially that Arteta has gone through the back of the player but there is nothing in it whatsoever. There is no real contact and I don't see how that is a yellow card."