After raising visions of an improved performance with a 4.5/5 start, Prasanna missed the thread of the position for the second day running and had to pay heavy dividends as Bernadskiy won in style.
The second straight loss left Prasanna on 4.5 points with no hopes for a podium finish.
International Master Ashwin Jayaram remained on course for a top-10 finish after settling for a quick draw with Grandmaster Vasil Spasov of Bulgaria.
Among other Indians in the fray, former world junior champion Abhijeet Gupta did some damage control in tournament after being lucky to score a full point against Bulgarian Mario Vutov.
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Swapnil Dhopade was held to a draw by Dagur Arngrimsson of Iceland, while Sagar Shah ended on the losing side against Melih Yurtseven of Turkey. Lower down, N Raghavi defeated Ivaylo Atanasov of Bulgaria.
Following a spate of draws at the top of the tables there was no change in standings at the top. As a result, over joint leaders, Tigran Petrosian and Hrant Melkumyan of Armenia and Vladislav Nevednichy of Romania continued to lead the tables with six points out of a possible seven.