Joshna, who is now India's highest-ranked player at 13, took 25 minutes to beat qualifier Megan Craig of New Zealand 11-8, 11-9, 11-6.
Dipika, ranked 16th, too faced little difficulty in her opener today, getting past Habiba Mohamed of Egypt 11-9, 11-2, 11-2.
Joshna faces Joelle King in the pre-quarterfinals tomorrow while Dipika takes on third seed Camille Serme of France.
Yesterday, World No.18 Saurav won a marathon contest against 20th-ranked Steve Coppinger, pipping the South African 9-11, 11-3, 12-10, 9-11, 11-9. He plays top seed Mohamed Elshorbagy of Egypt tomorrow.