Chennai, Jan 4 (IANS) Ten-year-old A Ra Harikrishnan, a student of local Sethu Baskara School, delivered the first upset in the SDAT - RMK 4th Chennai Open International Grandmaster chess tournament, defeating Woman Grandmaster and former National champion Nisha Mohota here Wednesday.

Obtaining an advantage in a hard-fought middle game, Harikrishnan (ELO 1755) led the game into an exchange-up ending. The Chennai boy handled the double rook versus a rook and bishop ending deftly to outwit the more experienced Mohota (ELO 2323).

The day offered a tough start for many seeds with International Masters Vijayalakshmi Subburaman, Suvrajit Saha and Vaibhav Suri conceding draws to lower rated opponents.

Top seed Grandmaster Aleksij Aleksandrov of Belarus had a relatively easy outing in the first board against Sarbajit Adhikari while defending champion and second seed Kravtsiv Martyn of Ukraine was stretched by S Vigneshwaran in the second board.

Running into the last few minutes of his allotted time, Martyn found his way to win thanks to checkmate threat through queen and bishop that fetched him an extra piece and the point.

Indian challenge led by Grandmasters Sethuraman, Deepan Chakkravarthy, Neelotpal Das and Dibyendu Barua took off smoothly with minimum resistance from lower seeds.

In all, 297 players including 16 Grandmasters, 31 International Masters, two WGMs and three WIMs from 15 countries are participating in this 11-round Swiss tournament that concludes Jan 12.

Results (Round 1): Aleksandrov Aleksej (Belarus) bt Sarbajit Adhikari, Vigneshwaran S lost to Kravtsiv Martyn (Ukraine), Barbosa Oliver (Philippines) bt Azikri Gur (Israel), Sanjit Saha lost to Oleksienko Mikhailo (Ukraine), Danielsen Henrik (Iceland) bt Alahakoon Isuru (Sri Lanka), Kotepalli Sai Nirupama lost to Sethuraman S P, Rahman Ziaur (Bangladesh) bt De Silva Osheen (Sri Lanka), Atul Kumar lost to Paragua Mark (Philippines), Bitoon Richard (Philippines) bt Rathanvel V S, Apurva G lost to Gomez John Paul (Philippines), Venkatesh M R bt Sai Prahlad K, Shrestha Lav Kumar (Nepal) lost to Deepan Chakkravarthy J, Yu Ruiyuan (China) bt Deep Kapoor, Arjun K lost to Dzhumaev Marat (Uzbekistan), Ma Qun (China) bt Rohan Ahuja, Anshuman K lost to Ashwin Jayaram, Neelotpal Das bt Hema Priya N, Ram Aravind L N lost to Barua Dibyendu, Thejkumar M S bt Anjana Krishna S, Shetye Siddhali drew Vaibhav Suri.