Both Om Prakash and Mayookha failed to rise to the occasion as they came up with below-par performances, much below their personal best, on the first day of the blue riband event.
Om Prakash, who trained for nearly two years at Szombathely in Hungary in the build-up to the Olympics, threw the 7.26 kg iron ball to a distance 19.86m, which placed him 10th in Group B and 19th overall.
His personal best is the national record 20.69m, which he recorded in May at his training base. Had he been even near his personal best, he would have easily gone through as the 12th and last final round qualifier threw a distance of 20.25m.
Those who crossed the qualifying distance of 20.65m or the best 12 make it to the final round.
The 25-year-old Indian cleared 19.40m in his opening attempt before covering the distance of 19.86m in his second.
He committed a foul in his third attempt.
American Reese Hoffa, who finished fifth in the World Championships in South Korea last year, led the qualifiers with an impressive throw of 21.36m, ahead of reigning world champion David Storl (21.15m) of Germany and 2008 Olympics gold winner Tomasz Majewski (21.03m) of Poland.
Beijing silver medallist Christian Cantwell of United States qualified in the final round at ninth with 20.41m.