Sale suffered an avulsion fracture to the lateral side of his right foot Friday at his spring training residence in Arizona, but the pitcher declined to reveal how the injury happened.
White Sox general manager Rick Hahn said Sale landed "awkwardly when he got off the back of his truck," while unloading items.
"It was really just a freak incident," Sale said. "I've just done it a million times and this time it didn't work out so well."
The White Sox say the left-hander's status for Opening Day will be determined at a later date. Sale already was scheduled to pitch in the first game of the season, but a return on March 21 would leave him just 16 days to prepare for the season opener at Kansas City.
"We'll have to assess how much arm strength he can build up prior to the opener," Hahn said. "Due to off days early in the season, we do not need a fifth starter -- so to speak -- potentially until April 12, so that would buy you another week before going to that spot.
"But we'll see. The most important thing is that this should heal completely in three weeks and then we'll go from there."
With his foot wrapped in ice and covered by an elastic bandage, Sale remained easygoing while talking about the injury, even joking that he fought off an intruder in grand superhero fashion.
"I mean, it's essentially a sprained ankle; I'll be fine," Sale said. "They aren't going to have to cut it off. It's still here. I'll be walking on it in a few days and just doing therapy."
Sale finished third in the American League Cy Young Award voting last season, going 12-4 with a 2.17 ERA. He pitched in just 174 innings after missing time early in the season with a forearm flexor strain.
Sale has dealt with an ailment early in each of his first three seasons as a White Sox starter, referring to them as no more than hiccups. His injury last season was the only one to force him to the disabled list.
"The [actual] best-case scenario [with the foot injury] would have been October 1, but I guess it's as good as it can possibly be," Sale said. "It's early, three weeks -- worst case, maybe a touch or two longer than that. But we are still here in spring. I don't see this trickling on into the regular season at all."