Former National champions B Adhiban and Krishnan Sasikiran raised their performance when it mattered and clinched their respective tie-break games to enter the second round of the chess World Cup here.
Pitted against a much higher-rated rival, Adhiban displayed top form to beat Evgeny Alekseev of Russia 5-3, winning in the blitz tiebreaker while Sasikiran prevailed over Constantin Lupulescu of Romania 2.5-1.5 cruising past in the second rapid game to reach the round of 64.
It turned out to be a bad day in office for other Indian contender Parimarjan Negi as he let go of his lead once again before going down to Yuri Kryvoruchko of Ukraine in the mini-match.
Parimarjan lost 2-4 but before that he won the first rapid tiebreaker as black. he blew it away with white pieces in the return game.
Adhiban's victory turned out to be the second biggest upset in the World cup so far after Wei Yi of China had beaten Ian Nepomniachtchi of Russia.
Ranked way below, Adhiban showed a lot of determination and played with his heart out to beat Alekseev, a member of the top 50 club it he world rankings.
It started with the rapid tiebreaker wherein Adhiban drew the first blood but lost the return game. The stage was thus set for two 10-minutes each games that ended in draws
Alekseev missed out on a clear advantage in the subsequent five-minutes each blitz game and ran out of time and in the second blitz game Adhiban gave no chances and picked up as many as three pawns before the Russian called it a day.
Sasikiran gave a perfect display of technical chess to outplay Lupulescu.
Playing the white side of a Queen pawn game in the second rapid tiebreaker after drawing the first, Sasikiran weakened the king side with some precise moves in the middle game and launched an attack on the king side to knock down a pawn for no compensation. The rest was child's play for the seasoned Indian.
Negi was unlucky yet again. In the normal games too he had won the first game with black pieces but could not make a draw as white and in the second too it was a similar story.
Winning with black with a fine combination, Negi got a balanced position again as white but missed out in the endgame to let Kryvoruchko level the scores again.
In the next set of tiebreakers, Kryvoruchko won both games. Sasikiran has a tough challenge to tackle in Sergey Karjakin of Russia in the next round of this USD 1.6 million event.
Adhiban will take on Alexander Fier of Brazil in what is expected to be an even contest.