Telugu Desam Party president N Chandrababu Naidu's son and Andhra Pradesh Information Technology minister Nara Lokesh lost his maiden electoral battle from Mangalagiri assembly constituency.
He was defeated by YSR Congress's sitting MLA Alla Ramakrishna Reddy by a margin of 5,337 votes.
In 2014, Reddy had won the seat by a margin of 12 votes.
Lokesh is currently a member of the AP Legislative Council.
His father-in-law and Telugu film star Nandamuri Harikrishna retained the Hindupur assembly seat by 17,028 votes. He defeated retired IPS officer Sheik Mohammad Iqbal of the YSRC.
The YSRC, which is set for a landslide victory in the 175-member AP Assembly, so far bagged 104 seats, as per ECI data. It is leading in another 46 seats.
The ruling TDP won 17 seats and is ahead in another seven.
The final results are expected by Friday morning.