Harding and the Wild have refused divulge whether his illness is related to his multiple sclerosis. He missed four games in December as doctors adjusted his medication for the disease.
"Wasn't feeling good, obviously," Harding said. "If I felt even a little bit like I could play, I would have. But there are some things that are out of my control."
Harding said he's been skating on his own for "three or four" days now, but Tuesday was seen as a major step toward getting him back in the lineup soon. Entering play Tuesday his 1.65 goals-against average is the best in the NHL and his .933 save percentage is second-best.
"The plan is to focus on [Tuesday]," Wild coach Mike Yeo said. "Obviously it's a good first step to get him on the ice."
Harding hasn't played since a 2-1 loss to the St. Louis Blues on Dec. 31.
Ottawa also got positive news on the injury front with forward Chris Neil close to returning from a hamstring injury. Neil has missed the Senators' past four games and hasn't suited up since Dec. 30.
"He probably could go if we absolutely needed him to," Senators coach Paul MacLean said. "But we really want to make sure, with the type of injury he has, that he's really ready to go. We want to make sure when he gets back in the lineup that he's playing in all the rest of the games and not just a couple."
Here are the projected lineups for the Senators and Wild:
Out: Chris Neil (hamstring)