Hairston singled to lead off the game and was injured when he stole second. He also stole third before scoring on Ken Griffey Jr.'s 600th career home run.
A team spokesman said Hairston would be examined Tuesday after the team returned to Cincinnati. Hairston said X-rays Monday night showed a non-displaced fracture and he could miss 2-to-4 weeks.
"Hopefully it's two weeks," he said. "I really feel comfortable getting a chance to play every day and leading off. But hey, I'll just come back and pick up where I left off."
Paul Janish replaced Hairston to start the bottom of the first.
Hairston's hit raised his average to .336 with one home run, 14 RBIs and 12 stolen bases. He was promoted from Triple-A Louisville on April 21.