Already without Sean Couturier (upper-body injury), Patrick Brown (MCL sprain), Derick Brassard (hip), and Nate Thompson (shoulder), the Flyers’ center position keeps taking hits this season.

The team announced Tuesday that center Kevin Hayes is expected to miss the next three to four weeks after undergoing a procedure in the morning to drain fluid from his adductor region.

“I think this was more, I would say, a doctor’s call, that something needed to be done,” interim coach Mike Yeo said. “But I shouldn’t get into specifics. But I think that will be something that Kevin can talk about. I think he’s supposed to be even at the game [Tuesday night], which is a good sign. But obviously, it’s a big loss for us.”

» READ MORE: Flyers’ Kevin Hayes makes emotional return to Boston for the first time since his brother Jimmy Hayes’ death

Yeo added that Hayes knew Monday that the procedure was scheduled to happen the following day, but he still wanted to go to Long Island to play in the Flyers’ first leg of a back-to-back against the New York Islanders. Although the timeline of Hayes’ recovery is three to four weeks, Yeo said Hayes could potentially return “even before that timeline says.”

With Hayes out of the lineup Tuesday, Yeo said forward Morgan Frost will move to third-line center. For Scott Laughton, who has been playing center on the second line with Couturier out and Giroux centering the first line, the absences of several centers mark opportunities for everyone to step up.

“You’re missing two of your top centers and Thommer [Nate Thompson] and Brownie [Patrick Brown] bring so many elements on the PK and faceoffs and things like that,” Laughton said. “Different guys are going to have opportunities and I’m one of those guys. I have to step up in a time like this. You have big shoes to fill, but you’ve got to do your job and be able to be relied upon when you’re playing against top opponents.”

Hayes missed the first month of the season after having abdominal surgery on Sept. 21, and made his debut Nov. 13. He played the following game against the Calgary Flames on Nov. 16 and scored his first goal of the season, but injured himself in the second period after getting tangled up with forward Elias Lindholm. Hayes returned to the game in the third period and participated in practice with the Flyers the next day.

After making a brief appearance at morning skate, Hayes was ruled out of the Flyers’ game against Tampa Bay on Nov. 18. Hayes returned to the lineup nearly three weeks later against the New York Rangers on Dec. 1 and hadn’t missed a game since then, playing through his injury despite not appearing 100% healthy. Through 20 games this season, Hayes has three goals and six assists.

“He’s been through a lot,” Yeo said. “I think, for him, being at the rink, being with the players, helping his teammates has done a lot for him. And obviously, he does a lot for us. So we’re just hoping that this is a quick recovery and we can get back on the ice soon.”

Willman returns to the lineup

After traveling to Long Island on Monday as a member of the taxi squad, the Flyers added forward Max Willman to the active roster for Tuesday’s game. Willman has played 19 games with the Flyers this season (two goals, one assist) and has slotted in at either left or right wing all throughout the lineup. With Frost moved up to the third line, Willman assumed the role of fourth-line left wing against the Islanders.

A native of Barnstable, Mass., Willman most recently appeared in the Flyers’ game against the Boston Bruins on Thursday. He racked up four penalty minutes, including a hooking penalty in the second period to set up a five-on-three for the Bruins that ended in a David Pastrňák goal.

Additionally, the Flyers sent forward Jackson Cates to the Lehigh Valley Phantoms from the taxi squad.

Breakaways

On the second night of a back-to-back against the Islanders, goalie Carter Hart (23 games played, .911 save percentage, 2.94 goals-against average) is expected to get the start in net. ... The NHL and NHLPA announced that after the All-Star break, the league will no longer be testing asymptomatic players and fully vaccinated close contacts. Testing will continue on a “for cause” basis for fully vaccinated club members who develop symptoms or require testing for travel across the Canadian border.