Granger received an injection in his left knee to treat patellar tendinosis, according to team officials.
The 29-year-old is regarded as one of the more under-rated players in the NBA. In his seventh season, Granger has an 18.2 career scoring average, and was an All-Star in 2009. The 6'8 small forward has led the Pacers to the playoffs in 2006, 2011, and 2012.
Granger enjoyed a typical season in the 2011-2012, averaging 18.7 points per game, and five rebounds.
The Pacers are off to a 2-2 record, but were expected to challenge for the Eastern Conference Central Division title, as the Chicago Bulls are still without injured star point guard Derrick Rose.
Indiana will likely rotate Gerald Green and Sam Young at small forward until Granger returns.