KANSAS CITY -- The 2018 Royals, already dealing with the loss of free agents Eric Hosmer and Lorenzo Cain, were dealt another serious blow on the eve of Opening Day.
All-Star and Gold Glove catcher Salvador Perez will be out four to six weeks after suffering a Grade 2 tear of the MCL in his left knee.
The injury occurred on Tuesday night after Perez had retrieved his Spring Training luggage from Kauffman Stadium. Perez was carrying a bag up a flight of stairs at his home in Kansas City when he fell.
"I missed a step and slipped and couldn't get my foot down," Perez said. "I heard a pop in my knee. After that I couldn't move my knee and couldn't take a step. I got scared and then I called [trainer] Nick [Kenney]."
An MRI on the knee Wednesday morning revealed the tear. Manager Ned Yost and Perez both said they did not think surgery would be necessary, and that the injury would scar over and heal on its own.
"I feel sad, not angry," said Perez, sporting a large elastic brace on the knee. "I put a lot of work in this spring and tomorrow I wanted to be there. What can you do? One second you're going to be there, then ...
"I was sad. I take Opening Day like it's the World Series. That's what you train for all offseason."
In 2012, Perez suffered a torn meniscus in the same knee and missed two months. But from 2013 and on, Perez started 647 games at catcher, tops in Major League Baseball.
For now, backup Andrew Butera will serve as the No. 1 catcher.
"He's our leader," Butera said of Perez. "He's our go-to guy. They're big shoes. But I feel like I'm capable of doing it.
"I honestly thought Ned was messing around with me when he told me the news. He came in and he said it. I kind of laughed. He looked like he had a little grin on his face. I had to ask three or four other people, 'Is he serious?'"
Yost also said Cam Gallagher likely would be recalled from Triple-A Omaha to serve as Butera's backup. Yost made clear that the Royals simply will have to adjust.
"It puts a pretty good hole in our lineup," Yost said. "Again, we'll deal with it.
"[General manager] Dayton [Moore] did a great job getting us Lucas Duda, Jonathan Jay and Moose [Mike Moustakas] in the lineup. We've been through [injuries] before."

Left-hander Danny Duffy, who will start Opening Day, said Perez will be difficult to replace.
"He's the heart and soul of our team, man, so losing somebody like him, he's obviously irreplaceable," Duffy said. "I told him today, 'We're gonna hold it down for you while you're gone. Don't worry about it. You're gonna be a huge part of this team, on or off the field. You always are.'
"Cam and Drew both call a really good game. ... As far as alternatives to Salvy, they're about as good as they come."