Without defenseman Ivan Provorov, the Flyers' chances of winning their Eastern Conference quarterfinal against the Penguins would go from slim to infinitesimal.

That's why the Flyers were holding their collective breath, hoping the standout second-year defenseman can play in Game 6 on Sunday afternoon at the Wells Fargo Center.

The two-time defending Stanley Cup champion Penguins lead the series, three games to two, and can advance with a victory.

Late in the Flyers' dramatic 4-2 win Friday in Pittsburgh, Provorov collided with Pittsburgh's Brian Dumoulin and crashed into the boards. It appeared Provorov's left shoulder took the brunt of the hit.

The good news: Provorov, whose 17 goals tied for the NHL lead among defensemen during the regular season, did not have a sling as he walked to the team bus after the game.

But general manager Ron Hextall would not give a medical update Saturday. Hextall is secretive during the regular season. During the playoffs, he turns into a CIA agent. His lips are sealed.

The Flyers had an optional practice Saturday in Voorhees, and, aside from their goalies, just one of their regulars, Matt Read, attended, so it is not known if Provorov will be available Sunday.

He played a career-high 30 minutes, 7 seconds Friday, helped contain Sidney Crosby, and was one of the stars of a penalty-killing unit that was 5 for 5 against the NHL's best power play.

For the first time in the series, Provorov and Andrew MacDonald started a game together Friday. MacDonald, who was together with Provorov early in the season, went to the top unit, and Shayne Gostisbehere (minus-8 in the series) was demoted to the second pairing, alongside rookie Robert Hagg.

If Provorov can't play Sunday, Gostsibehere might be paired with MacDonald, and Travis Sanheim would likely reenter the lineup.

The defense did a good job keeping the Penguins to the outside, and Michal Neuvirth stopped 30 of 32 shots in his first full game since Feb. 16.

When the playoffs started, Neuvirth was still rehabbing from a suspected groin injury, and Friday was his first start of the series.

And though he gave up two bad goals – a wraparound by Bryan Rust, and a through-the-legs tally by Jake Guentzel — Neuvirth made numerous clutch saves. The biggest: a glove stop on Sidney Crosby from the doorstep, keeping the Flyers ahead, 3-2, with 50 seconds left.

"He made some huge saves," captain Claude Giroux said. "When he plays cocky, he's pretty good."

"I like playing in the playoffs," said Neuvirth, whose postseason resume (a 2.00 goals-against average and .930 save percentage) reflects that notion. "I like facing the pressure."

The Flyers hope Neuvirth can channel the goaltender who extended their playoff series against Washington two years ago.

Trailing in that series, three games to none, Neuvirth replaced a struggling Steve Mason – much like he has replaced a laboring Brian Elliott in this series.

Neuvirth won Games 4 and 5 in that 2016 first-round series. He stopped 31 of 32 shots in a 2-1 win in Game 4, then blanked the Caps, 2-0, in Game 5, which the Flyers won despite getting outshot, 44-11. In Game 6, Neuvirth was again brilliant, turning aside 28 shots in a 1-0 Flyers loss.

In those three games, which were his only playoff appearances that season, Neuvirth had off-the-chart numbers: a 0.67 goals-against average and a (gulp) .981 save percentage.

And, still, it wasn't enough to beat Washington because the Flyers couldn't score.

They are hoping history doesn't repeat itself.