Uvis Balinskis also scored for the Panthers (21-11-2), who have won three straight and six of eight. Sergei Bobrovsky made 26 saves.
Oskar Sundqvist scored for the Blues (15-16-4), who have lost three in a row and five of their past six. Joel Hofer made 25 saves.
“It felt like an even game,” St. Louis coach Jim Montgomery said. “As we know, they are the defending Stanley Cup champions and have been a dominant team in this league for two and a half years now. It’s hard when you lose, especially when we had puck possession for much of the overtime. [Barkov] is a high-end player, and he made a high-end play, and then a big play on the power play. We had a lot of opportunities.’’
Sundqvist gave the Blues a 1-0 lead at 10:01 of the first period, shoveling a backhanded shot off the shoulder of Bobrovsky. He was fed a quick pass from behind the net by Alexandre Texier.
“We played a really good game. Felt this game could have gone either way,” Sundqvist said. “We had a bunch of scoring chances in the second, we should have capitalized more on. But I think we took a big step as a group. We went up against a really good team, and it could have gone either way.”