ATLANTA (AFP) - Atlanta Hawks scoring leader Al Horford will be sidelined indefinitely after suffering a torn right pectoral muscle, the National Basketball Association club announced on Friday.

Horford, who has averaged 18.6 points as well as 8.4 rebounds and 2.6 assists over 29 games this season, suffered the injury during the Hawks' double-overtime victory on Thursday at Cleveland.

"We will work with Al and complete our due diligence to determine the next best steps for him," Hawks president of basketball operations and general manager Danny Ferry said.

"Injuries are part of the challenge of an NBA season."

At 16-13, the Hawks are one of only three teams in the Eastern Conference with a winning record. But they trail defending NBA champions Miami (22-6) by 6.5 games in the Southeast division with Indiana (23-5) the only other East club above .500.

The Hawks will play their first game without Horford on Saturday when they entertain the Charlotte Bobcats.