Early in his career, Wirtz competed at the Canadian Championships in singles, ice dance, and fours, as well as pairs.

In the 1994–95 season, Sergeant/Wirtz won gold at the 1994 Skate Canada International, having placed seventh a year earlier, but dipped to fifth at the Canadian Championships.

The pair became national champions for the second time in 1999, where they had been widely expected to lose to the rising stars Jamie Sale and David Pelletier, who had posted better results on the grand prix circuit.

They had their best chance ever to medal at worlds that year, placing fourth after the short program, but two minor mistakes in the long dropped them to sixth, while the Polish bronze medallists had two major errors which would have left the door wide open for them had they skated cleanly.

They returned to competition for the 2002-2003 season, ending their amateur careers withdrawing prior to the long program at the 2003 Canadians with injury.