There were still nine changes to the side held at Sunderland, and only two or three could be confident of regular first-team football.
Like Wenger, Tottenham boss Harry Redknapp also opted for a mixture of youth and experience. But it did nothing to lessen the sense of occasion.
The atmosphere at White Hart Lane was terrific. So, for that matter, was some of the football, both teams playing with real purpose and fluency on a night that started with a minute’s applause for the late, great Bobby Smith.
But Arsenal showed greater poise and, to the delight of Wenger, secured the lead with what amounted to their first attack after 15 minutes. It was a delightfully executed goal.
A lovely touch from Rosicky was followed by a super ball across the face of goal and Lansbury sprinted off the right flank, arriving at the far post to convert.
Tottenham had created chances of their own, in the form of two efforts from David Bentley. He threatened with a free-kick as well as a shot from distance, but to no avail.
Although Roman Pavlyuchenko went closer still for Spurs with a shot that flew into the side-netting, players like Wilshere and Lansbury were continuing to impress alongside Nasri and Rosicky.
Arsenal were dominating possession, with Wilshere proving himself a fierce competitor in the heart of midfield against relative giants like Sandro and Jake Livermore, the latter picking up the first caution.
Frustration was beginning to creep into Tottenham’s football, the sight of Pavlyuchenko collecting the second booking of the night for a reckless challenge on Johan Djourou evidence of that.
A third Spurs yellow card soon followed for Kyle Naughton for a foul on Rosicky, although he was a little unlucky given how close he got to winning the challenge.
But this was becoming a tough contest for this weakened Spurs team, not least because of the difficulty they were experiencing in getting time on the ball.
The Arsenal supporters were delighting in the silence among the Spurs fans. Such are the rather relaxed rules in this country for a touchline ban, Wenger left the directors’ box shortly before the half-time whistle so he could spend the interval with his players.
But there was not much he needed to say. Not when they were playing as well as they were.
Redknapp would have been less amused, even if much of his anger would have been towards the Spurs fans for booing their team after just 45 minutes.
A little harsh, in fairness, particularly when Sandro and goalkeeper Stipe Pletikosa were making their debuts. Not exactly a welcome to north London.
Redknapp responded by making two changes and the arrival of Keane and Aaron Lennon quickly made a difference.
Within three minutes Keane had scored, albeit from an offside position and thanks in no small part to Fabianski. While the Irishman was offside when Naughton released his pass, Fabianski really should have saved what was a fairly weak shot.
As it was, he succeeded only in diverting the ball against his left-hand post before seeing it cross the line. A goal that propelled the match towards extra-time and penalties, but that was just one-way traffic.