ST. PAUL — It happened too fast. Josh Harding, the backup goalie for the Minnesota Wild, never saw starter Niklas Backstrom crumple to the ice during warm-ups Tuesday night. The Wild’s captain, Mikko Koivu, yelled for Harding to take over as trainers helped Backstrom to the dressing room at the United Center in Chicago with an apparent left leg injury.

There was no time for Harding to consider the moment: that he would become the first goaltender known to have multiple sclerosis to start an N.H.L. playoff game. Left wing Zach Parise skated up to Harding before the opening face-off to offer encouragement. Then Harding nearly stole Game 1 for the eighth-seeded Wild, stopping 35 of 37 shots against the top-seeded Blackhawks in a 2-1 overtime loss.

“He’s had a hard year,” Parise said. “We all know that. He’s gone through a lot. I was just telling him it’s his time now. I can imagine what’s going through his mind at that time in that circumstance. But I thought he rose to the occasion and played great. He gave us a lot of chances to win.”

Harding, 28, announced in October that he had M.S. and spent more than two months on injured reserve while adjusting to medication used to manage his condition. Fatigue can be troublesome for those with M.S., but Harding reported no problems after playing all 76 minutes 35 seconds Tuesday in his first start since Jan. 30.