Harris sat out Saturday night's game against the Washington Wizards and will leave the Nets' road trip Sunday to see a specialist in Chicago.
Harris said he's aiming to return in seven to 10 days.
"Maybe longer," he said. "It's not going to be shorter."
Harris originally hurt the groin in an exhibition game on Oct. 13 and reinjured it during Friday's loss to Orlando.
"I'm a little past frustrated right now," Harris said. "At this point, you've just got to wait it out."
Harris averaged 15 points, 7.5 assists and 5.5 rebounds in the Nets' first two games. He said his movement was restricted during Friday's game.
"I felt like I couldn't beat certain guys off the dribble," Harris said. "I can't play that way."
After his visit with the specialist, Harris will head to New Jersey. He said he wants to make sure the injury is completed healed before he returns.
"When I come back, I have to feel nothing -- nothing at all," Harris said.
Asked if he was afraid the injury was major, Harris groaned.
"No, of course not," he said, knocking his hand on his wooden cubicle. "Seven to 10 days."
Coach Lawrence Frank said the Nets want to "exhaust all options" to get Harris healed.
"With any player you want to do everything you can," Frank said, "to make sure he's healthy so it's not recurring."
Rafer Alston started in Harris' place Saturday.