The only team yet to win or lose in overtime this season and one of two without a defeat, the Wild relied on Fernandez to extend their streak.
Tkachuk got a pass from defenseman Chris Pronger at center ice with 84 seconds left and raced in alone on Fernandez. The goaltender made a blocker save on Tkachuk's wrist shot, then smothered the puck in the crease.
The Wild are one deadlock behind the mark set by Detroit, which tied all 15 overtime contests it played during the 1997-98 season.
Pierre-Marc Bouchard also scored for Minnesota.