The 29-year-old attacking midfielder, who scored the game's only goal in the 24th minute, smiled at the gaffe but his coach, Morten Olsen, seated beside him, was furious.
"Come on, come on," he snapped while turning to the official, "You've got to be better prepared if you are going to do something like that."
It was a little glimpse of the demanding approach Olsen takes to his players - and to anyone around him who fails to live up to his standards - but it didn't seem to upset Krohn-Dehli too much.
In two injury-plagued spells with Ajax, before and after a 12 game loan to Sparta Rotterdam, Krohn-Dehli managed just four appearances for the Netherland's top club.
"Its not like payback but it's nice when I've spent a lot of time in Holland and know a lot of people. I was unlucky with injuries at Ajax and that is part of the game, so there is no payback," he said.
Olsen was in more generous mood when describing the performance of a player who did what Netherland's Premier League top scorer Robin Van Persie couldn't - put away his chances.
"He was unlucky with injuries at Ajax but he was one of our best men in qualification, he is at his prime now and hope will play many years for us," he said.
"I made a mistake."
