Porto may have exceeded some expectations two weeks ago, but Arsenal's loss was, at its core, very much of their own making.
The two goals conceded were of such a bizarre nature that even club captain Cesc Fabregas, ever the diplomat, was reduced to describing the mistakes as "schoolboy".
And this isn't the first time Arsene Wenger's side have been bad-mouthed for their immaturity, with Patrice Evra's 'men against boys' jibes striking several nerves in north London. Add to this that Wenger as much as anyone has been described as a genuine scholar, or professor, within the game, and you have a perfect match.
Two to three months earlier than scheduled, in exam season.
And if Wenger's students were ever the type to carry cheat sheets with a bit of last-minute advice scrawled down, it's worth considering now what they might say...
Note to Manuel: Don't take back-passes from strangers. Or team-mates. Especially team-mates.
In all seriousness: Short on top sharpness, but key to his success will be shutting out all talk of Fabianski's first leg performance.
Strength: Synchronised posing.
Weakness: The ill-timed taking of a breather.
Note to Sol: Don't run with scissors. Or the ball. Or at all.
In all seriousness: Has gone from strength-to-strength since comeback, but needs to defend from deep, assuming he is fit enough to start.
Weakness: Not knowing quite where to run.
Note to Gael: Doing unto others as you would have them do to you does not fly here. Falling over so attacking opponents can run past you doesn't guarantee they'll return the favour.
In all seriousness: Bizarrely out of form and tormented in the first leg. Potentially vulnerable on the counterattack but can only improve.
Strength: Keeping us all guessing.
Note to Tomas: Get a matching scarf for those gloves and wrap up warm. Catching a cold could end your season. Then again, he could always pass it to Fabianski...
In all seriousness: Performance-per-player, not many if any in Arsenal's line-up this evening can match Rosicky. All well-spirited football fans will hope he stays fit and if he does, he's more than likely to play some part in any goals Arsenal get.
Strength: Not playing as a lone striker.
Note to Andrey: Think before you speak. Honesty, it would seem, isn't always the best policy.
In all seriousness: Outspoken criticisms aside, he can produce a moment of match-winning magic from nothing, but is short of both fitness and form.
Strength: Well, he's tall.
Weakness: A penchant for pub league football.
Note to Nicklas: No trainers in the dressing room, no pink boots on the pitch.
In all seriousness: He missed enough sitters to last a month or two in just one outing at the weekend. You'd think he's due one by now, but may struggle to get much joy from Bruno Alves.