As a junior, Petrova won the 1998 French Open, beating Jelena Dokić in the final. The same year she finished runner-up at the Orange Bowl to Elena Dementieva and she also finished runner-up at the junior 1999 US Open to Lina Krasnoroutskaya. In May 1998, she played her first WTA tournament at the J&S Cup as a wildcard entrant. She also received a wildcard for her home event in Moscow, the Kremlin Cup, where she picked up her first top twenty win over Iva Majoli. By the end of 1999, Petrova had reached the top 100.
In 2000, she reached the third round of the Australian Open and the quarterfinals of the Ericsson Open, beating Julie Halard-Decugis for her first top ten win before losing to Lindsay Davenport. She finished the season at No. 50. She reached the fourth round of both French Open and the US Open in 2001 and her ranking hit a high of No. 38 during the season. However, her 2002 season was marred by injuries causing her ranking to drop out of the top 100.









