KANSAS CITY, Mo. (TNS) — The Kansas City Royals received some bad news late Wednesday afternoon when it was learned that catcher Salvador Perez will be out four to six weeks with a torn knee ligament.

He slipped on a stair inside his house as he was lifting his suitcase Tuesday night, manager Ned Yost said. Perez appeared before the media Wednesday afternoon wearing a black brace on his left knee as he answered questions.

"I just lost my balance," Perez said.

The injury is a Grade 2 tear of the medial collateral ligament, the team said.

Perez had an MRI on the knee around midday on Wednesday. That's when the team learned the extent of the injury.

"He's distraught," Yost said. "Hopefully it (recovery time) is shorter than longer."

The Royals open the season on Thursday at Kauffman Stadium against the Chicago White Sox.

Yost said he doesn't think surgery will be necessary. But Perez expressed sadness about the injury, especially coming practically on the eve of the season.

"I'm sad," Perez said. "I don't feel angry. I feel bad, I feel sad."

Perez indicated that had gotten hurt while playing, that would be one thing. But to be injured on something fluky like falling on a staircase, that was another matter entirely.

"If I get hurt playing, that’s what I do," he said. "I play hard every day. That’s going to happen. ...

"All the work I do, training in the offseason, I feel sad."

The Royals open their 2018 season Thursday against the Chicago White Sox with many new faces, but one familiar face will be on the pitching mound in the person of left-hander Danny Duffy.