In March 2007, Kalac signed a contract extension with Milan, keeping him at the San Siro until at least 2009. In the 2007–08 season, he made appearances in the Champions League again after Dida was suspended for simulation in a match against Celtic, helping Milan through to the knockout phase. Kalac made a number of appearances in the Serie A, after Dida suffered a combination of injuries and poor form midway through the season. Kalac notably kept a clean sheet away to Fiorentina on 3 February 2008 as he snuffed out a Fiorentina attack moments before the final whistle, a save that earned praise from media and coach Carlo Ancelotti. Later in the month he collected another clean sheet at the Emirates Stadium against Arsenal in a 0–0 draw during the first leg of the UEFA Champions League round of sixteen, producing several good saves in the second half and being named Man of the Match by UEFA. In the second leg of the tie, he conceded two late goals as Milan were eliminated by Arsenal after a 2–0 loss at the San Siro.