"We don't know much else yet," Infante said.
But asked how long Infante would be out, Yost said, "Gonna be awhile."
Would Infante be back for the playoffs?
"Gonna be awhile," Yost said. "It's an oblique. Those things are long to heal."
The news was better for shortstop Alcides Escobar, who was hit on the left elbow with a pitch on Friday night. Escobar suffered a deep bruise, but could be back on Sunday.
"It's better than it was last night," Yost said. "They X-rayed it. Came up negative."
Asked if the Royals might bring up another middle infielder soon, Yost said, "We might.