Sindhu, the double World Championship bronze medallist, beat her world number eight Korean opponent 21-19 12-21 21-10 in a semifinal contest that lasted one hour and nine minutes.
The world number 12 Indian thus put herself on course for a fifth Grand Prix Gold event. She had won the same tournament in 2013 before bagging three more Grand Prix Gold tournament titles at the Macau Open (2013, 2014 and 2015).
From there, Sindhu nosed ahead by winning seven straight points. The Korean fought back but Sindhu did not let the advantage slip by as the Indian took the first set 21-19.
Sindhu, however, could not continue with the momentum in the second set as she played catch-up against Sung. The Indian narrowed down the gap in the score to just one point at 10-11 but from there she lost concentration and allowed the Korean to win seven straight points to concede the second set rather tamely at 12-21.
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India's top male player and world number 9 Kidambi Srikanth suffered a shock semifinal defeat at the hands of world number 51 Iskandar Zulkarnain.
The unseeded Malaysian outsmarted the second seed 27-25, 21-9 in the last four clash lasting 48 minutes.
Zulkarnain awaits the winner of the battle between top seed Lee Chong Wei and third seed Tommy Sugiarto in the final.