Michalek was placed on waivers by Toronto on Monday, Elliotte Friedman of Sportsnet reports.
Michalek will skate on the Leafs' top line beside Nazem Kadri to start the season.
Michalek potted a pair of goals in Thursday's 4-3 win over Team USA.
Michalek (knee) is healthy and ready to play with the Czech team in the World Cup of Hockey this fall, Sportsnet reports.
Michalek will miss the rest of the season with a knee injury.
Michalek suffered an undisclosed injury in Thursday's 4-1 loss in Buffalo, Dhiren Mahiban of The Canadian Press reports.
Michalek handed out two power-play assists Thursday in a 6-5 overtime win against the Ducks.
Michalek overcame a finger injury and made his Leafs debut Monday against the Sabres, picking up four hits and two PIM in 12:43 of ice time, including 1:32 on the man advantage.
Michalek indicated Sunday that he's "ready to go," for Monday's contest against the Sabres, the Kevin McGran of the Toronto Star reports.
Michalek (finger) anticipates making his team debut Monday against Buffalo, Terry Koshan of the Toronto Sun reports.