That doesn't look good, but at this writing it's being characterized as "just" a sprain. The Orioles will know more when Machado is re-evaluated on Tuesday. It's not certain how long he'll be sidelined.
At this point it's worth noting that Machado's start to the 2014 season was pushed back because of offseason surgery on the medial patellofemoral ligament in his left knee, not the one he injured on Monday.
Machado, 22, entered the night batting .277/.323/.428 in 352 plate appearances this season.