The year 2003 marked the beginning of the most successful period in Mukerji's career. She replaced Aishwarya Rai to play the lead opposite Shah Rukh Khan in Aziz Mirza's romance "Chalte Chalte". Media reports suggested that Rai was replaced after feuding with her then boyfriend Salman Khan on the film's sets, but Shah Rukh Khan insisted that Mukerji had been the original choice for the role. Mukerji believed that the theme of "Chalte Chalte", which dealt with misunderstandings between a married couple, was similar to that of "Saathiya", and she tried to lend variety to the role by putting "them against a different background". She has said that working with Shah Rukh Khan was a learning experience for her, and he would often scold her if she performed inadequately. A commercial success, Box Office India credited it as a career comeback for Mukerji, and she was rewarded with a second Best Actress nomination at Filmfare. None of her other releases of the year—"Chori Chori", "Calcutta Mail", and "LOC Kargil"—made a mark.