Royals catcher Salvador Perez will miss up to six weeks after spraining the medial collateral ligament in his left knee when he missed a step while carrying a suitcase up stairs in his home.

The injury occurred Tuesday night, when the club returned to Kansas City from spring training. The five-time All-Star heard a "pop" and immediately called Royals trainer Nick Kenney, who advised Perez to ice the knee and come in for an MRI exam on Wednesday.

The exam revealed a Grade 2 sprain with a minor tear of the ligament.

No surgery is required, and recovery can be as little as four weeks. The injury leaves the Royals without one of their top hitters when they open the season against the White Sox on Thursday.

Drew Butera and Cam Gallagher are expected to share catching duties in Perez's place.