Near the end of the season, Lumme was suspended two games for cross-checking Buffalo Sabres forward J. P. Dumont in a game on March 2, 2002. He also missed an additional four games with a shoulder injury. Following the trade from Dallas, he posted 12 points in 51 games for Toronto. During the 2002 playoffs, Lumme suffered a concussion and re-aggravated his shoulder during the second round against the Ottawa Senators. He suffered the injury after being hit into the boards by opposing forward Chris Neil. Sidelined for the remainder of the playoffs, he watched as the Leafs were eliminated by the Carolina Hurricanes in the semifinals.