ST. LOUIS (AP) Robby Fabbri broke out of a scoring funk and added to his hat collection in the process.
Perron deflected Colton Parayko's shot to tie it 5:53 into the third, less than two minutes after Schenn gave the Flyers a 3-2 lead. Perron ran his goal-scoring streak to three games.
Upshall put the Blues ahead 80 seconds later with a deflection of Joel Edmundson's shot. It was his first goal in 18 games.
''Our `D' did a great job of shooting with their heads up, getting them through that first layer,'' Upshall said. ''A goal of ours is to get in front of the net and be strong in those red areas and we did a great job. It was a big effort in the third for our team.''
Fabbri's second of the game with 4:59 left gave the Blues insurance, and he added an empty-netter for the hat trick two minutes later.
''Everyone was sticking to the game plan and knowing what was making us successful,'' Fabbri said.
Parayko, who had two assists, said there was no panic after falling behind in the third.
''We pushed and got two right away to go up 4-3,'' Parayko said. ''The best part was we didn't fall back on the 4-3 lead like we have been.''
Simmonds scored his team-leading 17th goal just 3:25 into the game, tipping in a backdoor pass from Travis Konecny into a wide open net.
Shattenkirk tied it with a power-play goal with 4:59 left in the first. Six of Shattenkirk's eight goals this season have come with the man advantage.
Fabbri made it 2-1 with another power-play goal with 11 seconds left in the opening period.
''We were our own enemies tonight,'' Mason said. ''Overall, it wasn't a great game for us. We're going to have to be a lot better.''
It was the first career hat trick for Fabbri, who snapped a seven-game scoring drought.
''The break really helped him,'' Blues coach Ken Hitchcock said. ''He was really beat up. And getting four days off helped him heal. He was really hurting the last four, five games. He was able just to barely play, but he feels good physically and I think you can see it in the jump in his game.''
The Blues had multiple power-play goals in a game for the first time since they went 3 for 7 against Tampa Bay on Dec. 1.
''It seems like we've been going in streaks here with the power play,'' Fabbri said. ''Good start with Shatty's goal there. We just gotta keep that going and have the consistency.''
Schenn gave the Flyers a 3-2 lead at the 4:13 mark of the third period with a power-play goal, his seventh goal this month.
''We wanted just too easy of a night; we wanted to play too easy of a game,'' Flyers coach Dave Hakstol said. ''We have to be better and will address that.''
NOTES: Shattenkirk played in his 400th game as a Blue and become the 12th defenseman to reach that plateau with the team. ... Flyers C Sean Couturier returned after missing 16 games with a lower-body injury. ... The Flyers and Blues were the only teams in the NHL to have had a full five days in between games over the Christmas break.
Flyers: Travel to San Jose on Friday night.
Blues: Host Nashville on Friday night.
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