World No. 22 Kashyap played out of his skin to avenge his loss to Ouseph, who had beaten him at the 2010 Delhi Games and also dumped him during the mixed team event at the Emirates Arena here.
In a gruelling one hour and 23 minute match, Kashyap bounced back from a game down to edge out World No. 26 Ouseph 18-21 21-17 21-18 and assure himself of at least a silver medal.
However, Sindhu, who is playing her first Commonwealth Games, could not go the distance in women's singles as she went down fighting to Michelle Li of Canada 22-20 22-20 in the last-four encounter.
This is her second defeat to Li at the Emirates Arena. Sindhu had lost to the Hong Kong-born shuttler during the Mixed team event.
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The Hyderabad girl will meet the winner of Malaysia's Jing Yi Tee and Scotland's Kirsty Gilmour in the bronze medal contest.
Prakash Padukone had won the men's singles gold medal at the 1978 Commonwealth Games in Edmonton, Canada, which India retained through Syed Modi four years later.
It was a battle of attrition between Kashyap,27, and Ouseph as both the shuttlers engaged themselves in long energy-sapping rallies, with the longest going on for 72 minutes in the decider, which had a total of 71 strokes.