Nilsson was only 29 years old when he played his last major league season, hitting a 309/.400/.554 clip with 21 home runs for the 1999 Milwaukee Brewers season. He was also fit enough to play catcher regularly for the club for the first time in five years. In the 1999 All-Star Game, he replaced Mike Lieberthal as the National League catcher, becoming the first (and until being joined by Grant Balfour in 2013, the only) Australian to play in a Major League Baseball All-Star Game.