Schjønberg made a memorable appearance in the penultimate match of the 1999–2000 season. In the game against SC Freiburg, first-choice goalkeeper Georg Koch was injured and the substitute goalkeeper Uwe Gospodarek replaced him. By the half-time break, Gospodarek had suffered an injury of his own, and with no more goalkeepers selected for the match squad, Schjønberg took over the keeper's gloves. In the 59th minute, Levan Kobiashvili scored against Schjønberg to give SC Freiburg a 2–1 lead, but Schjønberg otherwise kept his sheet clean. He crowned his achievement with a saved penalty kick, when he held the shot from Alexander Iashvili in the 84th minute.