The Penguins and Flyers might both be missing a key forward Wednesday in Game 4 at the Wells Fargo Center.

The Penguins announced that right winger Patric Hornqvist, who has played on the first and second lines and has three points in the series, will be out with a lower-body injury. He had 29 goals – including a team-high 15 on the power play – during the regular season.

The Flyers could be without top-line center Sean Couturier, who was injured during Tuesday's practice when he collided with teammate Radko Gudas. Couturier was helped off the ice and limped to the locker room.

"I didn't see him, and he didn't see me," Gudas said. "Tough break."

"It didn't look good …but I'm not going to jump to conclusions," captain Claude Giroux said.

The Flyers said they would not have a medical update until Wednesday, but Couturier was in lots of pain and might have injured a knee.

There was one person who was upbeat.

" 'Coots' will be fine," right winger Wayne Simmonds predicted.

Couturier, 25, set career highs in goals (31) and points (76) in the regular season. In the playoffs, he leads the Flyers with three points – all in a 5-1 win in Game 2.

If Couturier can't play, rookie center Nolan Patrick would probably move from the second to the top line, though another option would be to shift Giroux from left wing to center.

Should Couturier be unavailable, "we'll have that [lineup] answer at game time," coach Dave Hakstol said.

Couturier has four goals (three in one game) and seven points in 22 career playoff games, while Hornqvist has 36 points, including 20 goals, in 75 career playoff games.

Hornqvist, 31, is listed as day to day. At the Penguins' practice Tuesday, Dominik Simon, 23, took his spot on the top line with center Sidney Crosby and left winger Jake Guentzel. Guentzel took Hornqvist's spot on the top power-play unit.

Simon has not played in the series, and he had 12 points, including four goals, in 33 regular-season games.

"Guys are going to get the opportunity to step up," Penguins coach Mike Sullivan told reporters after the Penguins' practice, adding that Hornqvist "isn't an easy guy to replace."

Hornqvist was one of the Penguins' top players down the stretch, scoring nine goals in the final 11 games of the regular season. Pittsburgh's power play has clicked at 26.2 percent with Hornqvist in the lineup, and just 12.9 percent (4 for 31) in four regular-season games without him, according to the Post-Gazette.

Odd series

It's been a strange series that has had three one-sided games.

Pittsburgh won the opener, 7-0, but the Flyers took Game 2, 5-1.

The Penguins withstood the Flyers' first-period dominance in Game 3 and won, 5-1, to take a 2-1 lead in the best-of-seven series. Pittsburgh was 3 for 7 on the power play in that game, and the Flyers need to show more discipline Wednesday.

"When you're down a game, it's time to respond," Flyers goalie Brian Elliott said. "They came back at us and now it's our turn."

Breakaways

The Penguins were a poor even-strength team during the regular season, but they have outscored the Flyers, 8-3, in five-on-five play during the series. … Jordan Weal will play in his first career playoff game Wednesday. … Michal Neuvirth is day to day and there's a slight chance he will serve as Elliott's backup Wednesday. … The Flyers' defensive pairings will remain the same, based on Tuesday's practice.