Thirty million euros is a lot to spend on an 18-year-old. Then he curls one past the English champions and you stop counting.
Karetsas did exactly that on Sunday. Borussia Dortmund beat Arsenal 3-2 in normal time to win the Emirates Cup. The Greek teenager announced himself with a left-footed finish just before the half-hour and BVB Buzz handed him a glowing mark in its player ratings against Arsenal.
Die Schwarzgelben paid Genk €30m to land him on a five-year deal, one of the priciest arrivals in the club's history. He creates from behind the striker, or off the right. Sound familiar?
A debut that reshaped the queue
Here's the thing. Dortmund lost their two most creative forwards this summer.
Julian Brandt walked out on a free and popped up at Ajax. Karim Adeyemi cashed in and joined Barcelona. That's two of last season's front three out the door.
Kovač sets up in a 3-4-2-1, with two support men feeding Serhou Guirassy, who has struggled in pre-season and could find himself behind Fabio Silva come opening day of the Bundesliga. Those are the seats everyone wants. And a teenager has just planted himself in one of them on day one.
BVB Buzz introduced him as the new playmaker who scored on debut. That billing will stick if the goals keep coming. Heavy stuff for a kid of 18. He looks ready for it.
Who feels the squeeze now
Spare a thought for Maximilian Beier. Last season he shuttled between the second striker role and the flank. Now a record signing has jumped the queue ahead of him.
Felix Nmecha can rest easier. He is tied down until 2030 and does his sharpest work deeper, so he and Karetsas can share a midfield rather than a shirt. Beier is the one with a fight on his hands.
The academy kids over at Brackel will be watching too. BVB built their name on backing youth, and here is fresh proof that a teenager can walk straight into the side if he is good enough.
Schalke are only just back in the Bundesliga, promoted last season. The Champions League football Karetsas is stepping into remains a distant dream for die Knappen.
One pre-season strike settles nothing. Guirassy is the fixed point up top. Those two support slots will churn through a long campaign across the Bundesliga and Europe.
Karetsas got the first word in, though. Beier and the rest have to respond.
Verdict: an early sign the record kid can handle it.
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