"I'm not sure what's going to happen with Roberto," Tortorella said. "Lack will play [Sunday] and we'll see where we go from there."
The Vancouver Province reported Luongo will be out 7-10 days with a possible groin injury.
Luongo is 19-9-6 with a 2.24 goals-against average and .920 save percentage. Lack is 6-2-0 with a 1.93 GAA and .928 save percentage.
"We have total confidence in [Lack's] play," Tortorella said.
The Canucks on Friday recalled goaltender Joacim Eriksson from the Utica Comets of the American Hockey League to serve as Lack's backup. Eriksson is 8-10-1 with a 2.77 GAA and .907 save percentage in the AHL. He has not played an NHL game.