The victim, Dinesh Bhavchandani, was riding back to his house, when two men on a motorcycle threw acid on him, the police said.
Bhavchandani had given a statement against Asaram Bapu in the rape case against him. The victim was taken to a private hospital for treatment.
This however is not the first time when witnesses in the Asaram and Narayan Sai rape cases have been attacked. Earlier also two witnesses were attacked by unidentified people.
The police on questioning said that though all the witnesses are given police protection, three of the witnesses had refused to take the police cover.
With PTI inputs