Seeded 12th, Mary Kom (48kg) was up against a rather gritty Mongolian Altansetseg Lutsaikhan. But the five-time world and Asian champion gained the upper hand with her aggressive approach in the first two rounds.
The Manipuri did seem drained in the final three minutes but managed to connect just enough blows to come up trumps.
Mary Kom will face Philippine's Josie Gabuco who sent second seed and local favourite Monika packing with a dominating performance.
Both the boxers fought hard in a bout fought on counter- attack but Manish got the judges' nod for perhaps being a shade better on accuracy.
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This was Shiva's second loss to Manish after the national championships final last year.
"I am slightly faster than him. I managed to deceive him by counter-attacking. He attacked more but I managed to dodge that," the 21-year-old Manish, who is employed with the Indian Army, told PTI.
Former Commonwealth Games gold-medallist Manoj Kumar (69kg) also made a shock exit after going down in a split decision to compatriot Dinesh in another fiercely-contested bout.
In contrast, Asian bronze-medallist and light flyweight (49kg) top seed Amit Panghal advanced to the final after a split verdict over compatriot Nutlai Lalbiakimma.
Three-time King's Cup gold-medallist K Shyam Kumar (49kg), and Asian Games bronze-medallist Satish Kumar (+91kg) also made the finals.
But Asian silver-medallist Sumit Sangwan (91kg), who sustained a cut during his semifinal clash, gave a walkover owing to his injury.
Sarita stood out for being a better power-puncher than her opponent and managed to connect a few telling blows to Priyanka's torso. Sarita will face Finland's Olympic and world bronze-medallist Mira Potkonen in her summit clash.
"She hits very hard, her punches have a lot of power. I have to primarily guard against that," Sarita said about her final opponent.
Potkonen ousted second seed and home favourite Pavithra in her last-four stage clash.
However, world youth champion and top seed Shashi Chopra (57kg) was upstaged by compatriot Sonia in a rather bizarre contest in which both the boxers ended up being cautioned for being too defensive.
Eventually, Sonia prevailed in a unanimous verdict for perhaps being a shade more attacking and accurate than Shashi.
Sonia will face Filipino Nesthy Petecio, who defeated Indonesia's Christian Marwam Jembay.
Also ending with a bronze medal was former world silver- winner Sarjubala Devi (51kg). Sarjubala went down in a split 3-2 verdict to Mongolian Jargalan Ochirbat.
Simranjit was beaten by Thailand's Sudaporn Seesondee. Seesondee will square off against local favourite Pwilao Basumatary in the final.