"He is unavailable to our hockey club for a minimum of one week," coach Randy Carlyle said. "We are looking at it probably 7-10 days."
Komarov sustained the injury in the second period of a shootout loss Thursday to the Buffalo Sabres.
The 26-year-old ranks third in the League with 126 hits and his loss will be especially felt by the Maple Leafs when they face the physical Boston Bruins on Saturday night.
Ryan Hamilton, recently recalled from the Toronto Marlies of the American Hockey League, will enter the lineup in place of Komarov. Carlyle said Hamilton will initially skate on a line with Mikhail Grabovski at center and Matt Frattin on right wing but could be elevated to play on the top line with Tyler Bozak and Phil Kessel.
Bruins coach Claude Julien said forward Rich Peverley will be back in the lineup after being a healthy scratch in Boston’s previous game against the Ottawa Senators. Defenseman Johnny Boychuk will not play because of a lower-body injury, which means Matt Bartkowski will play in his first game of the season.
Injured: Leo Komarov (upper body)
Scratched: Ryan Spooner
Injured: Johnny Boychuk (lower body)