Then released her Enakku 20 Unakku 18 which was unsuccessful commercially but was a well noticed film because of its music and visuals and helped her career. Following Lesa Lesa, she appeared in Alai which proved unsuccessful at the box office. The romantic musical, based on the 1998 Malayalam film Summer in Bethlehem, fetched generally positive reviews. Lesa Lesa, which was supposed to be her début, released next. The masala flick became the biggest blockbuster of the year, grossing ₹ 16 crores, and landed Trisha new offers, including several high-budget productions. She played a soft-spoken college-going Brahmin girl and received positive feedbacks for her performance, with Sify's reviewer citing that she was "appealingly sensual" and looked "glamorous", and another critic writing that she looked "very pretty" and suited the role. Her subsequent release was the Hari-directed police film, Saamy with Vikram. Manasellam, her second project, saw her play a cancer patient but the film went unnoticed despite positive reviews for the film and the actress. The film became a moderate success at the box office and managed to gain credentials for Trisha, with critics claiming that she was "undoubtedly a refreshing new find, with sparkling eyes and appealing demeanour", also going onto praise the dubbing artiste, Savitha Reddy, who has since regularly dubbed for Trisha. However both the projects' releases were severely delayed, and her first release was Ameer's Mounam Pesiyadhe opposite Surya Sivakumar. The first project she accepted was the Priyadarshan-directed Lesa Lesa, with the promotional posters for the film, also creating an offer to star in the A R Rahman musical hit, Enakku 20 Unakku 18 (2003). Soon after her pageant success, Trisha began her acting career in a minor supporting role as Simran's friend in Jodi. Main article: Trisha filmography 1999–2003: Early career and success However, she compensated by attending summer classes. She followed a tight shooting schedule while in college, making it difficult for her to continue her education.
She was later approached for an acting role in the Tamil movie Lesa Lesa by Indian film director Priyadarshan, which marked the beginning of her professional career as an actress. She also appeared in Falguni Pathak's music video Meri Chunar Udd Udd Jaye as Ayesha Takia's friend, which was directed by Radhika Rao and Vinay Sapru. Trisha had aspired to become a criminal psychologist initially, and resisted the thought of pursuing acting, as she wanted to complete her studies first. She had also won the Miss India 2001 pageant's "Beautiful Smile" award.
In 1999, she won the "Miss Salem" beauty pageant, and later the same year, the Miss Chennai contest. She ventured into modelling and appeared in several print and television commercials. She completed schooling at the Sacred Heart Matriculation School in Church Park, Chennai, and later pursued a Bachelor of Business Administration (BBA) course at the Ethiraj College for Women (Chennai). Trisha Krishan was born to Krishnan and Uma in Chennai (then known as Madras) into a Tamil Palakkad Iyer family.