Maurice Smith tightened his grip on the gold medal when he further extended his overall advantage to 172 points with the longest throw of the event.
The Jamaican, competing in one of his favourite disciplines, racked up an impressive 920 points from his 52.36m effort, even though he was more than three metres shy of his lifetime best.
Second placed Dmitriy Karpov at least gleaned some satisfaction by extending his lead on the bronze medal position occupied by Roman Sebrle by five points with a best of 48.95m (849 points).
However, Sebrle gave himself an outside shot at the gold by digging deep to throw 48.75m and come within 0.62 of his lifetime best with his final effort.
The Czech, who picked up 844 points from the seventh event, now trails Smith by 221, but with the potentially medal-defining pole vault next up, the Czech has at least given himself a distant hope of adding the world title to his Olympic and European crowns.
In the blazing heat at the Nagai Stadium the field in pool B started tentatively. Karpov opened with a sloppy 45.42m and let out a grunt of despair at his effort.
Smith opted for a safety-first approach in round one and the discus bounced off the sun-baked turf in the Nagai Stadium at 49.02 – almost six metres shy of his lifetime best of 55.69m.
Meanwhile, Sebrle was also a little down on his season’s best with 46.95m. But the second round witnessed significant improvements.
Karpov and Smith went out to 48.95m and 52.36m respectively, and Sebrle also advanced with 47.98m.
In the final round Karpov, in his desperation to find greater distance, overbalanced in the circle and committed a foul, which looked to be in the 48-49m range. Smith with 51.44m could not improve upon his big second round effort, but Sebrle showed the true character of a great champion by saving his best until last.
Behind the medal positions the Russian duo of Aleksey Drozdov and Aleksey Sysoyev advanced up to fourth and fifth in the overall standings after 48.62m and 49.76m throws, respectively.
Cuban teenager Yordani Garcia slipped from fourth to sixth after producing a best effort of 42.91.
The 2003 World champion Tom Pappas, who was holding sixth position, did not start the discus and withdrew from the competition
Overall standings after seven events
1, Smith 6431
2, Karpov 6259
3, Sebrle 6210
Osaka 2007 News Team/sl