Leading by four shots overnight, Siddikur made life difficult for himself with a wobbly final round of three-over-par 75, allowing the chasing pack to hound him down.
Chowrasia, who has won twice before at the fabled Delhi venue, agonisingly missed a five-foot birdie chance on the last hole to force a play-off, as Siddikur ended a three-year winless run following his career breakthrough at the 2010 Brunei Open.
Lahiri, who closed with a 70, shared second place with Chowrasia in the $1.25 million tournament as he also rued a missed birdie chance on the last hole to force extra time in front of a large gallery.
“I am so happy. After I won in Brunei, I struggled to win a tournament,” Siddikur was quoted as saying by organisers.