The much-maligned Arsenal manager out-witted his Spanish counterpart when the sides met in the FA Cup semi-final in April before causing an even bigger upset to outplay recently-crowned Premier league champions Chelsea in the final.
Neither sane Arsenal and Chelsea followers will deny the balance of footballing power has shifted this season up north to the Etihad and their same-city rivals United.
But this match once again showed that there is life in Wenger and his players yet when it comes to one-off cup ties.
Chelsea have played Arsenal five times in competitive matches since their Wembley humiliation (if one includes the Community Shield) and Antonio Conte still cannot get the better of his French rival.
And when Chelsea just about edged the first half of this semi-final second leg after their early Eden Hazard opening goal was cancelled out by Nacho Monreal’s deflected equaliser, Wenger made a key and rare change of tactics to win the match at half-time.
With a dearth of options to improve things on his substitute’s bench, Wenger switched his line-up for the start of second half by going to a three-man defence (including an out-of-position Mohammed Elneny) and allowing his more attack-minded midfielders Alex Iwobi and Granit Xhaka more freedom to get forward.
It nullified much of Chelsea’s attacking threat from the flanks too and caught Conte and his players by surprise.
The less said about Iwobi and why Wenger persists to play him probably the better here, but by the time Arsenal had taken the lead through Xhaka’s close range poked shot on the hour, Chelsea had not recorded an attack of note after the break.
It is fair to assume that new signing Henrikh Mkhitaryan will replace Iwobi when he is eligible to play after his switch from Manchester United.
For surely the Armenian will be more effective in front of goal than the Nigerian was when presented with a great chance to out the tie beyond doubt.
But with the new boy cup-tied last night and for the Wembley date with City on 25 February (ironically the same day they were due to play a league game here) there will probably be even more urgency asked of Arsenal’s transfer men camped out in Dortmund trying to find Dortmund’s magic number to sell them Pierre-Emerick Aubameyang.
For despite this win it is still only Arsenal’s second victory of 2018 and Chelsea are almost as fragile.
Positive results, of course, can quickly restore a brittle brain to a solid one, but Guardiola will not have lost a lot of sleep after watching this keenly-contested London derby.
That is not to say Arsenal were poor or in anyway lucky. Far from it.
They followed their manager’s game-plan and worked tirelessly in the knowledge their boss has Conte’s number.
The Italian started without a recognised forward in his line-up and has been talking like a dead man walking since before the season started.
That is something that can never be said of the Arsenal manager, who is often criticised for not being tactical flexible and over-optimistic about his team’s abilities.
But he had the last laugh for one special night last night.
Wenger has never won this competition having been to the final twice losing to Chelsea in Cardiff and Birmingham City more recently at Wembley.
Their FA Cup heroics were supposed to translate into a league title tilt this season, but nothing could be further from the truth.
They look likely to miss out on Europe altogether the way things are going — unless this competition or the Europa League can save them.
Only time will tell if his name is finally on the trophy in what some experts are saying could and should be his final season.
And if he does it against Pep’s marvels then what a way to bow out that will be!