The former Air Force officer played a big role in moulding Usha into India's most prolific athlete on the international arena.
Mixed doubles pair of Satwiksairaj Rankireddy and Ashwini Ponnappa produced a spirited performance before going down narrowly to top seeds Dechapol Puavaranukroh and Sapsiree Taerattanachai in the semifinals.
Saina is going through the toughest phase of her career and needs to take care of herself so as to avoid any more defeats, says the former national champion and coach.
Satwiksairaj Rankireddy and Ashwini Ponappa stunned world No. 6 pair of Peng Soon Chan and Liu Ying Goh of Malaysia in a nail-biting mixed doubles quarterfinal.
World No. 31, who had shocked Malaysia's eighth seed Lee Zii Jia in the opening round, needed just 39 minutes to see off Rasmus Gemke 21-12, 21-9.
Prannoy recovered from a game down to outwit sixth seed Christie 18-21, 21-16, 23-21 in a thrilling contest that clocked an hour and 15 minutes.
It was Saina's fourth straight loss to world No. 12 Busanan.
The world badminton champion took to Instagram to express her greetings.
Parupalli Kashyap exited from the tournament after he retired in the third game of his first-round clash against Canada's Jason Anthony Ho-Shue owing to a calf injury.
It was a chaotic day and the entire procedure put us under severe mental stress, the duo told Malayala Manorama.