David Backes scored at 9:04 of overtime on a shot that deflected off a Chicago Blackhawks defenseman, and the St. Louis Blues took the series opener 1-0 over the defending Stanley Cup champions on Wednesday night.
Backes' shot got past Corey Crawford after bouncing off Trevor Van Riemsdyk's skate.
Defensemen Jay Bouwmeester and Alex Pietrangelo assisted on the winner.
Brian Elliott earned his first career playoff shutout. Elliott, who led the NHL with a .930 save percentage, made 35 saves to thwart a lineup led by scoring champion Patrick Kane and Jonathan Toews. He made just his second playoff start in three seasons off an impressive finish, going 11-1 in his final 14 starts.