An MRI taken Saturday confirmed the injury to the Spurs' star guard, who was hurt during a 99-83 loss to the Miami Heat on Friday -- two nights after scoring a career-high 55 points against the Minnesota Timberwolves.
Parker was driving for a layup when he rolled his ankle.
The 26-year-old Parker was using crutches and wearing a protective boot while watching Sunday's practice. He was second in the league in scoring behind LeBron James at 27.4 points per game.
The Spurs are 1-4 and play at home against the New York Knicks on Tuesday. In 1996, they opened the season 1-5.
"You'll probably get to see George play a lot," Spurs president R.C. Buford said. "We'll continue to evaluate not only our team, but the NBA market as we go along. Our guys have been encouraged with what George has done to date."
One of the last cuts the Spurs made in the preseason was fourth-year point guard Salim Stoudamire, who has not been signed by another team.
The Spurs are also missing Manu Ginobili, who is expected to be out until December while recovering from ankle surgery. He participated in cutting and shooting drills during Sunday's practice.
"I don't think we can comment on Manu other than to say that he continues to progress as prescribed," Buford said.
Hill has played 35 minutes since being drafted 26th overall out of Indiana University-Purdue University at Indianapolis. He played 10 minutes after Parker left Friday, missing three shots from the floor. He finished with one point, an assist and a turnover.
The 33-year-old Vaughn was inactive, though no injury was listed. He dressed but did not play Wednesday at Minnesota. He averaged 10 minutes in the Spurs' first four games this season.