Granderson and the team had hoped the injury was merely a bruise. But precautionary X-rays revealed the break.
Granderson, who was wearing a splint on the hand Sunday, said he likely will miss a minimum of three weeks.
"It throbs a little bit," he said.
Until then, one of the most energetic Tigers won't be able to play at all -- and Brandon Inge will likely be in centerfield when the season opens one week from today at Comerica Park.
"He's got to play out there all week," Tigers manager Jim Leyland said, according to the Detroit Free Press. "Andy [Van Slyke, the outfield coach] thinks four or five days and he'll be fine."
Granderson, who batted .302 last year with 23 homers, said he will probably see another doctor Sunday night. He expects to have more X-rays in two weeks, at which time he hopes to be cleared to return to baseball activities. He said it probably would be another week before he's ready to play.
Information from The Associated Press is included in this report