Forward Colby Armstrong also sustained an injury during the contest, breaking his nose as he was bloodied in a fight with defenseman Dennis Seidenberg. He is listed as day-to-day.
Lupul could be done for the season, as he may not see much more action this season as the Leafs currently sit in 12th place in the Eastern Conference, five points out of playoff contention.
Lupul's long-term absence is a tough blow for the Leafs as the forward is second in scoring for the team with 25 goals and 42 assists for 67 points in 66 games.
