Jaden Schwartz scored his second goal of the game 30 seconds into overtime to give St. Louis a 2-1 victory over the Boston Bruins on Wednesday night.
The Blues won for the fifth time in six games to move within two points of the final Western Conference wild-card spot.
Jake Allen made 21 saves to improve to 24-21-2.
Ryan Donato scored for Boston. The Bruins clinched a playoff spot and moved within four points of Tampa Bay for the Eastern lead.
Schwartz scored his third game-winning goal of the season with a nifty coast-to-coast march in the extra period. He took a drop pass from Colton Parayko and skated behind his own net to gain momentum.
Schwartz weaved through a pair of defenders and drilled a hard shot from the slot past goalie Anton Khudobin, who made 18 saves.
Schwartz, who got his 15th career game-winner, missed 20 games earlier in the season with a broken ankle.
Schwartz tied it midway through the third period with a wrist shot from the top of the circle.
Donato scored his second goal in his second NHL game. He had a goal and two assists in a 5-4 loss to Columbus on Monday night.
The Blues host Vancouver on Friday night.