Prakash, who got a wild card entry into the main draw, was leading 6-3 3-2 when Serbian Llija Bojoljac opted out of contest, thus clearing the way for the Indian to the next stage.
Prakash will now fight it out with third seed and local favourite Jesse Levine for a place in the quarterfinals.
Prakash and his American partner Alex Kuznetsov have already booked a quarterfinal berth in the doubles event.
Another Indian in the fray is Harsh Mankad, who has teamed up with Treat Conard Huey of Philippines.
The third seeded combo will play its opening encounter against Grega Zemlja of Slovakia and Roko Karanusic of Croatia.