Columbus Crew's MLS Cup hopes have been dealt a "big blow" coach Caleb Porter acknowledged Friday with word that Darlington Nagbe and Pedro Santos have been ruled out of Saturday's title clash with Seattle Sounders.

The team said Thursday night that both players were "medically not cleared to play," and Nagbe tweeted on Friday that he had tested positive for Covid-19 but had no symptoms.

"Obviously losing Pedro and Darlington, we lost one of those two early in the week. We had a positive test. Then we had two straight days of all negatives. We had another positive that popped up," Porter told reporters on Friday.

"I learned that in the middle of training yesterday. Of course, it's a big loss. It's a big blow. Those two guys have been key players for us on a personal level, a human level. If you just take away the soccer, I just feel for them. Obviously they're healthy, so that's first and foremost the most important thing.

"But I just feel for them on a personal level, a human level, that they can't be a part of an MLS Cup that they so deserve to be a part of."

Both have played key roles in the Crew's run to a third MLS Cup final appearance. Nagbe, a two-time MLS Cup winner, has been superb under pressure and is unarguably the league's most accurate passer.

A defensive workhorse, he also scored the league's Goal of the Year with his only goal of the season -- a sensational volley in Columbus' 3-0 win over Chicago in August.

Santos, meanwhile, had six goals and delivered the key pass in eight more in the regular season and added two more goals in the MLS Cup playoffs.

The duo join Dutch central defender Vito Wormgoor as the only players on the Crew's injury report.

Danny Leyva was the only player listed on the Sounders' injury report with the 17-year-old out with a right quad strain.

Porter said he believed his side could still emerge winners against a Sounders team vying for a second straight MLS Cup crown and a third in five years.

"You have to be mentally strong," Porter said. "We're going to find a way to perform well and to hopefully win, even though we've of course lost two of our very best players."

The Crew host the Sounders in MLS' title match on Saturday.

Sounders coach Brian Schmetzer said the absence of Nagbe and Santos wouldn't change how he prepares his players to take on the Crew.

"Those are two super-talented players," Schmetzer said. "Caleb is going to put two other talented players on the field in their place. He still has the advantage of being at home.

"There is nothing that I would prepare differently because we prepared for a very good opponent, many different ways."