Jhanvi Kapoor cut her wrist outside Prateeksha, the Bachchans' bungalow in Juhu, claiming she unable to bear Abhishek Bachchan's marriage to Aishwarya Rai later in the day.
Kapoor tried to file a complaint against Bachchan Jr with the Juhu police, but the complaint has not been registered. In an ironic twist, she has been arrested for attempting to commit suicide.
"We didn't register a complaint as Jhanvi Kapoor had no case," said police officer A. Mohite. "This is a stunt."
Red and pink flowers, encircled by gold and green curtains, covered a huge air-conditioned tent in a garden adjoining the Bachchan family home where Rai and Bachchan will exchange garlands and wedding vows later Friday.
Police tightened security around the venue as the guest list was a who's who of India's rich and famous — including movie stars, top industrialists and politicians.
Fans and the media have been crowding around Bachchan's residence since pre-wedding ceremonies began two days ago. Some came bearing boxes of sweets and said they wanted to bless the couple.
Kapoor created a stir as she arrived at the Bachchan's house early Friday and slashed her wrist. She was given first-aid treatment at a nearby hospital.
Police recorded her statement, but said she appeared to have been taking drugs.
"She showed us no proof and her speech was slurred," Mohite said. "She seemed to have done this purely to catch the attention of the media."
Mohite also said Kapoor didn't give her real name and police have information that she was already married.
She had slit her wrist in the past also, he added.
Meanwhile television channels claim that Kapoor is a divorcee and was married to one of the sons of Maulana Kalbe Sadiq of the Muslim Personal Law Board in Lucknow.
Kalbe Sadiq, who was out of the country, has confirmed that Kapoor's real name was Naina Rizvi and that she was his former daughter-in-law.
Kapoor, however, has denied this.
She claimed her father was a Kapoor and that he died when she was a year old. Later, her mother was remarried to a Muslim. 'I was never married,' Kapoor insisted. 'My mother is in Scotland and I have been in Mumbai for nearly two years now,' she added.
Sporting a bandaged arm, she told reporters she loved Bachchan, who had promised to marry her.
To a question whether the Bollywood star reciprocated her love, she said: "He is not talking to me. I want to know why he doesn't talk to me." Kapoor was one of the 10 dancers in a promotional music video for a movie "Dus" (Ten) that Bachchan starred in two years ago, he said.