Thabang Mnisi, the son of Deputy Minister of Public Service and Administration Ayanda Dlodlo, alleges that Pienaar and a group of his friends assaulted him in the VIP section of Icon, a luxury nightclub in Sandton.
Pienaar turned himself in to the Sandton police station on June 18, following the allegations.
Sowetan reports that Mnisi failed to attend a scheduled identity parade at the Sandton police station on Tuesday, and was also absent from court yesterday.
Through his lawyer Cliff Alexander, Pienaar told the Sowetan outside court yesterday that he was not guilty.
"I did not assault the complainant. I admit I was present at the club that night, but I did not assault anyone," he said.
Alexander further said that Mnisi had not specified who assaulted him, and that video footage would put Pienaar, who flew into the country for the court hearing, in the clear.
Prosecutor Samantha Manning yesterday asked the court to grant the state a postponement because investigations were incomplete and an identification parade still needs to be held.
The case has been postponed to September 6 and Pienaar was released on a warning.