PHILADELPHIA -- Midway through the second period Monday night, a sloppy turnover resulted in an easy goal and 3-0 deficit for the Philadelphia Flyers.

Even worse, they followed it up with a penalty. At the moment, it looked like their holiday break was going to be spoiled by a blowout loss.

However, the Flyers remarkably turned the penalty into a short-handed goal to ignite a furious four-goal rally and beat the St. Louis Blues 4-3 at Wells Fargo Center.

"We gave up the third goal the way we did," Philadelphia coach Dave Hakstol said. "Sometimes that can be the nail in the coffin."

But it wasn't as the Flyers (15-12-7) completed their biggest comeback since Dec. 19, 2013, to improve to 8-2-2 in the past 12 games.

"When you put the effort in and you work hard, good things happen," goalie Steve Mason (7-8-5) said after making 26 saves in the win. "I think it took us 30 minutes to wake up, but when we did, we took over the game and it was a lot of fun to watch those guys go to work."

Defenseman Evgeny Medvedev punctuated the comeback with the winning goal at 16:47 of the third period when he scored on a slap shot off a nice pass from center Ryan White.

Right winger Wayne Simmonds scored the Flyers' second and third goals to tie it, both assisted by left winger Jakub Voracek and Shayne Gostisbehere.

For the Blues (20-11-4), they wasted an opportunity to win their fourth straight game by failing to knock out the Flyers when they had them wobbling.

"It's just our lack of burying that team when we have a 3-0 lead, never giving them life," center David Backes said. "You never know what this turns into. You get life and we're on the losing side and get zero points when we should have two."

St. Louis remains tied for second in the Central Division behind the Dallas Stars with one game left before the break.

"Just foot off the gas again," Backes said. "We haven't put together a full 60 and bury a team when we have a three-goal lead, which seems like the logical thing to do."

Blues goalie Jake Allen (15-8-2) was under heavy siege and stopped 27 shots. St. Louis didn't help him as Philadelphia made its push.

"There were a lot of poor puck decisions in the second period," Blues coach Ken Hitchcock said. "(The Flyers) dialed it up in the second period and we started turning it over.

"We didn't manage it very well at all. It was in the offensive zone that really hurt us. We lost a lot of one-on-ones that exposed us."

The Flyers knotted the score 51 seconds into the third period to complete their climb back. On a power play that transferred from the second into the third, Simmonds got a piece of a shot from Voracek to deflect it home.

"I think we talked about it, we don't want to go into the break on a losing note," Simmonds said. "We thought we'd been playing really, really good hockey of late, so I thought it was only right for us to go into the break with a win."

Center Robby Fabbri opened the scoring 8:16 into the game by beating Mason, who was scrambling across the crease after making a save to his left. Right winger Dmitrij Jaskin took the rebound behind the net and fed Fabbri for a Blues 1-0 lead.

After Voracek was penalized for roughing during a scrum in front of St. Louis' bench, the Blues took advantage on the power play when defenseman Kevin Shattenkirk laced a slap shot past Mason with 5:09 left in the period.

In the second period, the Blues took a 3-0 lead as left winger Magnus Paajarvi scored an easy one on a wide-open breakaway off a bad turnover by defenseman Michael Del Zotto.

"No panic," Simmonds said. "We've been saying that for a long time now."

With his team up against the wall on the penalty kill, right winger Pierre-Edouard Bellemare intercepted a pass at center ice and was stuffed by Allen on a breakaway, but hustling center Chris VandeVelde muscled home the second-chance opportunity for a short-handed goal.

"The short-handed goal hurt us a lot," Hitchcock said. "It gave them momentum."

Back came the Flyers 2:10 later, trimming the deficit to one when Simmonds and Voracek nicely executed an odd-man rush with a give-and-go, capped by Simmonds beating Allen top shelf.

Simmonds then did it again in the third before Medvedev sent the Flyers home happy.

"It just goes to show, when you put the effort in and guys are competing hard, that's what type of team we can be," Mason said. "That's not an easy team to do what we just did against."

NOTES: Blues D Joel Edmundson, who was recalled on Sunday from American Hockey League affiliate Chicago, returned to the lineup and played his first game since Dec. 5. RW Jordan Caron, who was also recalled, was a healthy scratch. He's expected to play Tuesday against the Boston Bruins. ... Flyers D Mark Streit (groin) remained out of the Flyers' lineup, while C Sam Gagner, who has not played since Nov. 23 because of an upper-body injury, is healthy but was a scratch Monday. ... C Patrik Berglund (shoulder), LW Jaden Schwartz (ankle), C Steve Ott (hamstring) and C Kyle Brodziak (lower body) were all sidelined for the Blues. ... Flyers D Brandon Manning was a healthy scratch for the second straight game as D Luke Schenn played his second in a row in his place. Flyers C Vincent Lecavalier was also a healthy scratch.