"We played a little rope-a-dope," coach Barry Trotz said. "We got great goaltending and won the game on special teams."
Defenseman Kevin Klein got the go-ahead goal at 13:14 of the third, less than a minute after Jason Arnott tied it only four seconds into a tripping penalty call on Cal O'Reilly. Legwand added an empty-netter.
"Obviously, I think defense first," Klein said. "But they definitely talked to me before the year and said they want everyone to jump in the play and be a two-way defenseman."
Blues coach Davis Payne called Klein's goal "a back-breaker." Forward T.J. Oshie thought he may have screened Halak.
"A little miscommunication in the D-zone," Oshie said. "I don't even know if he saw it. Just a small mistake and they capitalized on it."
Craig Smith had a goal and two assists for the Predators, starting the season strong with a pair of road victories on consecutive nights coming off their first appearance in the Western Conference semifinals. They won despite getting outshot 33-16, scoring three times on just five shots in the third.
"Two divisions opponents, too, going into their barn and winning," Legwand said. "Weathering the storm, that's big for our team and our confidence."
Patrik Berglund also scored for the Blues, who were 8-1-1 at home to start last season.
"We'll call this speed bump in the road No. 1, nothing to panic about," captain David Backes said. "We outshot them 2 to 1, we just didn't bury our chances, and they did."
Halak hadn't allowed a goal in 171 minutes, 15 seconds against the Predators before Smith scored on a rebound shot in the first period to tie it at 1. Halak entered the season with 114 minutes and 55 seconds of shutout play.
"It's really tough to stand there, to get one shot in five minutes and then wait for another one," Halak said. "They always want to play a tight game, score a few lucky goals or a few bounces. It's hard to play against this team."
Legwand was credited with a power-play goal that put Nashville up 2-1 early in the third after his pass across the crease trickled into the net off defenseman Nikita Nikitin's skate.
"At times we clicked," Payne said "At times they misfired."
Nashville had 31 shots in a 3-2 victory at Columbus on Friday night.
Blues defenseman Carlo Colaiacovo landed hard with his back and head into the end boards after getting upended by Blake Geoffrion at 13:16 of the second and did not return. The team said he had an upper body injury.
"No update for right now," Payne said. "We'll just check back on him in the morning. A little bit awkward situation."
A taped message from Blues forward David Perron, out since last November with a concussion, drew the biggest cheers in the Band of Brothers-style pre-game ceremony. Perron is skating with the team, but there's no timetable for his return.
Blues public address announcer Tom Calhoun worked his 1,108th consecutive home game. ... Backes debuted as Blues captain. He's only the second forward since 1997 (Dallas Drake 2005-07) to be captain since 1997. ... Arnott was the Predators captain from 2007-10. ... Halak fell to 6-2-1 against the Predators.