Chawrasia, who scored 71, 71 and 69 in the last three rounds, had to endure a frustrating day as he carded a horrendous seven-over 78 on the final round to slip 28 places to tied 50th.
Lahiri, on the other hand, brought home an improved one-over 72 in the final round to stay static at the 57th spot.
The Olympic golf course barred its fangs to Chawrasia as he dropped a triple bogey at the third, a bogey at seventh and a birdie at eighth to make the turn at two-over. He then stumbled on a bogey patch from 11th to 14th hole, which also included a double bogey at the 13th.
Britain's Justin Rose (67), Sweden's Henrik Stenson (68) and USA's Matt Kuchar (63) won the gold, silver and bronze respectively after totalling 268, 270 and 271 after four rounds.
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