Marcus Foligno had a goal and an assist and Cam Talbot made 25 saves for the Wild (43-20-5), who are 9-0-1 during the streak and moved five points ahead of the St. Louis Blues for second place in the Central Division. Jordan Greenway had three assists.
The line of Eriksson Ek, Foligno and Greenway combined for eight points (three goals, five assists) for Minnesota, which won the second of a back to back after a 3-1 victory at the Carolina Hurricanes on Saturday.
"We like playing them against top lines clearly, and we get out here and we're just going to roll lines and get what we get, and it probably frees them up a little bit," Wild coach Dean Evason said. "It's nice for guys that do the dirty work, do the grinding, do the checking to get rewarded sometimes too."
Garnet Hathaway scored, and Vitek Vanecek allowed four goals on 18 shots for the Capitals (37-22-10), who have been outscored 11-2 in their past two games and have lost four of six. They trail the Boston Bruins by seven points for the first wild card into the Stanley Cup Playoffs from the Eastern Conference.
"I think turnovers, bad decisions with the puck, that kind of killed our momentum," Washington captain Alex Ovechkin said. "When we put the puck deep, forecheck, we all know what we have to do, just [tonight] for some reason we try to make a cute play, you know. I think we just have to forget this game."
Eriksson Ek gave the Wild a 1-0 lead 36 seconds into the game. Alex Goligoski held the puck behind their net, then passed up to Greenway beyond center ice. Eriksson Ek received Greenway's tap pass, got behind the defense and shot between Vanecek's pads.