Jason Zucker is week to week with a lower-body injury, Penguins coach Mike Sullivan said.
The forward left late in the second period of a 2-1 win against the Dallas Stars on Monday but returned for the third. Zucker is fourth on the Penguins with 20 points (six goals, 14 assists) in 27 games.
Zucker and Jeff Petry will not play at the Florida Panthers on Thursday (7 p.m. ET; BSFL, ATTSN-PT, ESPN+, SN NOW).
Petry was placed on long-term injured reserve Tuesday, retroactive to Dec. 11, with an upper-body injury. By being placed on LTIR, the 35-year-old defenseman will be out for a minimum of 24 days and 10 games.
"We've got other guys that we're going to put in the lineup that, once again, we believe we have capable guys," Sullivan said. "We have enough to win. It's going to provide opportunities for others to step up and play more significant roles."
Danton Heinen, a healthy scratch in five of the past seven games, moved into Zucker's spot at left wing on the second line with center Evgeni Malkin and right wing Bryan Rust in practice Wednesday.
Kris Letang, who was out five games after having a stroke Nov. 28, has replaced Petry on the top defense pair with Marcus Pettersson.
Zucker missed two games with an undisclosed injury earlier this season before returning Oct. 29. He was sidelined 41 games with various injuries last season.
"We feel for 'Zuck' because he's played extremely well for us," Sullivan said. "It's been a struggle since he's been a Penguin just keeping him healthy."
Petry said he was fine after leaving a 3-1 win against the Buffalo Sabres on Dec. 10 with 1:51 remaining in the third following a hit into the boards by Sabres forward Alex Tuch. He missed the win against the Stars on Monday that extended the Penguins' winning streak to six games.
Petry has 12 points (three goals, nine assists) in 28 games this season, his first with Pittsburgh after he was acquired in a trade with the Montreal Canadiens on July 16.
Forward Drew O'Connor and defenseman Mark Friedman were recalled from Wilkes-Barre/Scranton of the AHL. -- Wes Crosby