Timmins has been diagnosed with mononucleosis and is considered out indefinitely, Mark Masters of TSN reports. He was moved to injured reserve Tuesday, per the NHL media site.
The Maple Leafs will want to be sure Timmins is no longer contagious before allowing him to rejoin the team. The 25-year-old defender has picked up six points while averaging just 15:45 of ice time through 16 top-level appearances this year.