"They've painted both pictures, and it's a pretty big window," manager Don Mattingly said Wednesday. "We're guessing."
Ramirez was hurt diving for a ball while playing third base Tuesday night in the championship game of the World Baseball Classic. He helped the Dominican Republic beat Puerto Rico 3-0.
Ramirez was set to have an MRI on Wednesday night after returning to Dodgers camp. Mattingly said a mild sprain would likely leave the All-Star infielder out for a couple of weeks, but a major injury would make it much longer.
"They're going from a guy coming out of a big game, to a guy who also stayed in the game and had a single," Mattingly said.
"Until the MRI, we're guessing. He could be feeling great, we don't know. We're concerned enough to get an MRI. He's coming out of a game, a pretty big game - guys don't want to come out of those."
Miguel Tejada eventually replaced Ramirez in the championship game.
Ramirez hit .271 with 10 homers and 44 RBIs in 64 games last season with the Dodgers after being acquired in a trade with Miami.
Luis Cruz, who was projected to play third base for Los Angeles, started at shortstop Wednesday against Kansas City. Mattingly said Cruz would the first choice at shortstop if Ramirez is out for a while. That would open up third base for Nick Punto, Juan Uribe or Jerry Hairston Jr.