Fernandez, who was moving toward returning to regular playing time, reinjured the medial collateral ligament in his left knee in Tuesday's victory over St. Louis and has been sidelined since.
"I want to get back as soon as I can," Fernandez said, according to Sunday's Pioneer Press. "It's not fun to sit around and watch games. My main goal is to always be on the ice. This is not a good position for me. It's tough to keep up morale. For now, it's back on the [exercise] bike."
An MRI taken on Friday did not reveal any new damage, the St. Paul Pioneer Press reported, but the healing period will take longer.
"Two to four weeks from the time of the injury," assistant general manager Tom Lynn told the Pioneer Press, "so that's one to three weeks from now. That's probably being a little optimistic. Once we get him back on the ice, we have to get him ready."
Niklas Backstrom was in goal for the Wild on Saturday night and stopped 29 shots for his second shutout of the season, a 1-0 victory over the Phoenix Coyotes. The Wild recalled Josh Harding before Friday's game against Colorado to serve as Backstrom's backup.
"It's not a good thing to lose your top goalie at this time," Wild coach Jacques Lemaire said, according to the Pioneer Press, "but for Backstrom, it is a good thing. It gives him a chance. It's going to be a great experience."