The Serb scored 2-0 in the 13th minute and played until 1-0 already after 45 seconds in the 2-1 victory, just the day after he was left out of the squad.
Tadic was one of several players - including goalkeeper André Onana and midfielders Davy Klaassen and Ryan Gravenberch - who were not included in the reduced list of players due to positive tests, but were given the green light to play after being tested negative before the match.
"Must be ready"
Afterwards, Tadic was tight-lipped about the situation.
- The most important thing was that we took three points, he told Dutch SBS6.
- As a professional, you have to do everything you can to always be ready, regardless of whether you play or not.
Listened to the phone
Coach Erik ten Hag describes the last few days as "crazy".
- On Monday we did not know who would play against Midtjylland.
We called in Davy Klaassen so late that he did not even have time to come to the player hotel.
He had to go directly to the arena and listen to the match review on the phone on the way.
Ajax is second in Group D, five points behind Liverpool and ahead of Atalanta thanks to a better goal difference.
Both have four points.
CLIP: Meet Midtjylland's Swedish shooting star Jens Cajuste
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National team star: The talent Cajuste about the choice between Sweden and the USA