"Disappointment is the only way to describe the feeling in our dressing room," PA quotes the Dane as saying. "I have tried it myself - I have been on the winning side and the losing side in derby games.
"It's always easy to brag when you win, but sometimes you have to stand up even when the other team come out on top. You have to take the defeat and say: 'Okay, we lost this time'. You have to accept it and remember there's always a next time.
"We all knew how important this game was to the fans, the players, the staff, everybody. Losing is always a disappointment, but it is even more in these games."
The Swans play host to Cardiff in the return fixture at the Liberty Stadium in February.