MAMALLAPURAM: Teenaged Grandmaster D Gukesh shocked world number 5 Fabiano Caruana as India 'B' pulled off a superb 3-1 win over number 2 seeds USA in the eighth round of the Open section of the 44th Chess Olympiad here on Saturday.
Gukesh is enjoying a purple patch and his victory over Caruana was his eighth on the trot in the tournament and helped improve his live ratings.
He moved up to second behind the legendary Viswanathan Anand in live ratings.
His splendid run has been the key behind the success of the India 'B' team, seen by many as the darkhorse of the championship.
Fellow teen and GM Raunak Sadhwani (Elo 2611) stunned higher rated GM Linier Dominiguez Perez (Elo 2754) in 45 moves as India 'B' shut out USA.
GMs Nihal Sarin and R Praggnanandhaa drew their games against Levon Aronian and Wesley So respectively.
''From the beginning we had all intention of figuring in the top-3 and with Gukesh going such great guns, it very much looks a possibility,'' said a thrilled RB Ramesh, the coach of India B.
''Fabiano is my favourite player and it was a pleasure to be pitted against him. Initially, I was caught in the opening as it went along unfamiliar lines for me. I was slightly worse. After he played a dubious move, I got back into the game,'' said Gukesh, who clinched the game on the 45th move.
This is one of the most impressive debuts in the history of the Olympiad. Only the former world champion Vladimir Kramnik set a record of 8.5/9 in 1992, clocking a 2958 rating performance. Till seventh round, Gukesh had clocked a 3300 plus performance.
In other matches, second-seeded India 'A' lost to Armenia 1.5-2.5, while India 'C' suffered a 1-3 defeat against Peru.
GMs Vidit Santosh Gujrathi, Arjun Erigaisi and S L Narayanan drew against Hrant Melkumyan, Samvel Ter-Sahakyan and Robert Hovhannisyan respectively but P Harikrishna lost to Gabriel Sargissian on the top board to hand Armenia a crucial win.
In the women's event, India 'B' thrashed Croatia by 3.5-0.5 score.
Meanwhile, India 'A', who had been going great guns with seven victories before this match, were held to a 2-2 draw by second-seeded Ukraine in an intensely fought encounter while India 'C' lost to Poland by 1-3.
Despite the loss, India 'A' continued to be sole leader with 15 points, followed by Georgia (14 points). All the four matches in the India 'A' vs Ukraine clash ended in a stalemate. The highly-rated Muzychuk sisters -- Mariya and Anna -- drew against Koneru Humpy and D Harika respectively.
India 'B' team rode on wins by Vantika Agrawal, Padmini Rout and Divya Deshmukh to thrash Croatia.
Results: India's matches: Open: India A lost to Armenia 1.5-2.5 (P Harikrishna lost to Gabriel Sargissian, Vidit Gujrathi drew with Hrant Melkumyan, Arjun Erigaisi drew with Ter Sahakyan, SL Narayanan drew with Robert Hovhannisyan).
India B beat USA 3-1 (D Gukesh beat Fabiano Caruana, Nihal Sarin drew with Lev Aronian, R Praggnanandhaa lost to Wesley So, Raunak Sadhwani beat Linier Dominguez Perez).
India C lost to Peru 1-3 (Surya Shekhar Ganguly lost to Emilio Cordova, S P Sethuraman drew with Cristhian Cruz, Abhijeet Gupta lost to Renato Terry, Karthikeyan Murali drew with Vera Siguenas).
Women: India A drew against Ukraine 2-2 (Koneru Humpy drew with Mariya Muzychuk, D Harika drew with Anna Muzychuk, R Vaishali drew with Anna Ushenina, Tania Sachdev drew with Nataliya Buksa).
India C lost to Poland 1-3 (Easha Karavade drew with Alina Kashlinskaya, P V Nandhidhaa lost to Oliwia Kiolbasa, Pratyusha Bodda lost to Maria Malicka, Vishwa Vasnawala drew with Michalina Rudzinska).
India B beat Croatia 3.5-0.5 (Vantika Agrawal beat Mirjana Medic, Padmini Rout beat Anamarija Radikovic, Mary Ann Gomes drew with Tihana Ivekovic, Divya Deshmukh beat Tereza Dejanovic).