Goalie Carter Hart left Tuesday’s practice early because of an injury and, as a precaution, the Flyers put Alex Lyon on a plane to St. Louis, sources said.

Lyon could serve as Brian Elliott’s backup against the St. Louis Blues on Wednesday.

General manager Chuck Fletcher said he would not have a medical update on Hart until Wednesday.

“Obviously, he felt a little something. I’m not really sure where in the lower-body region," coach Alain Vigneault said after practice Tuesday.

Vigneault said “everything was fine” with Hart after he was the winner in Monday’s 6-5 shootout victory over Boston. “And everything was fine this morning, so I’m not quite sure what happened in the time they were warming up the goalies and I’m stepping on the ice. Two minutes after, he was stepping out.”

Vigneault said Elliott was scheduled to play in St. Louis on Wednesday even before Hart left the ice with assistant trainer Sal Raffa.

Hart is 15-11-3 with a 2.61 goals-against average and .905 save percentage.

Elliott, who is 9-5-3 with a 3.16 GAA and .896 save percentage, will face the defending Stanley Cup-champion Blues, his former team.

If Hart isn’t healthy enough, Lyon, who has a 2.56 GAA and .916 save percentage with the Phantoms, would serve as Elliott’s backup Wednesday. The Flyers would need to send another player to Lehigh Valley because they don’t have enough cap space.

Up next: Berube, defending champs

The Flyers will face yet another NHL heavyweight as they meet the defending Stanley Cup champion Blues in St. Louis.

Despite playing most of the season without the injured Vladimir Tarasenko (shoulder), a star winger, the Blues (30-10-7) entered Tuesday tied with Washington for the most points in the NHL.

The Flyers have gone 2-1 over their last three games, all against elite teams: Washington, Tampa Bay, and Boston.

“They’re one of the hottest teams in the league right now, so it’s another great challenge for us, another opportunity to prove we can be one of those teams,” center Sean Couturier said of the Blues.

Directed by Craig Berube, the ex-Flyers player and coach, St. Louis is winning because of its sturdy defense, which is allowing just 2.60 goals per game, fourth in the NHL.

“You have to bring your 'A' game; it’s a tough building to play in,” Elliott said. “I’ve been on the other side of it there.”

Facing his former team “makes it a little extra special,” Elliott said. “I think the guys recognize that and try to give you that little extra effort.”

Breakaways

Defenseman Justin Braun, who originally was supposed to be sidelined for the rest of January because of a groin injury, is making a speedy recovery and could return Saturday against the Kings or (more likely) next Tuesday against the Penguins, according to GM Chuck Fletcher. ... Shayne Gostisbehere had knee surgery Tuesday and is expected to return Jan. 31 in Pittsburgh, Fletcher said, adding that defenseman Egor Zamula, an impressive prospect, will have season-ending back surgery and will miss the rest of the Western Hockey League season. “This will allow him to be healthier going forward and it’s the right thing for his career,” Fletcher said of the surgery. “The expectation is he’ll be back for next year.”