The Philadelphia Union likely will enter Sunday's MLS Eastern Conference final against visiting New York City FC without the majority of their regular starters due to a COVID-19 crisis.

The No. 2-seeded Union listed 11 players as "out" in the league's health and safety protocols on their club's official availability report prior to the showdown in Chester, Pa.

That includes six starters and eight players total of the 15 who featured in Philadelphia's triumph on penalties over Nashville SC following a 0-0 draw in last weekend's East semifinal.

All four of Philadelphia's starting defenders and goalkeeper Andre Blake are among those out.

Union manager Jim Curtin was aware of the possibility he would be short-handed in Sunday's game during remarks he made Friday, though he couldn't delve into specifics.

"Our players have worked tirelessly to get to this point," Curtin said. "I know they'll be brave even in the adversity that we're facing. We've stepped up in big moments all year long. Be it international absences, the challenges of Concacaf, players losing loved ones. Adversity on and off the field, this group always finds a way to step up. We will make our fans proud."

Fourth-seeded New York City FC will be far closer to full strength, but they will be missing 2021 MLS Golden Boot winner Valentin Castellanos.

The Argentine attacker received his second yellow card in the 113th minute of extra time as NYCFC defeated the New England Revolution on penalties following a 2-2 draw.

Four minutes earlier, Castellanos scored his second playoff goal after putting up 19 in the regular season.

Heber or Talles Magno are options to replace Castellanos. Heber scored 15 MLS goals in 2019. But after tearing his ACL the following season, he has only made seven appearances and played 95 minutes in total this campaign.

"A player like Heber has done it in this league and has shown me many times, and I almost feel a little bit sad that I haven't used him more because (Castellanos) has been unbelievable," said NYCFC manager Ronny Deila.

"It will be important to have both Talles and Heber," Deila added. "And we're going to use both of them in the game I'm sure."