Penalty-corner ace Sandeep Singh scored seven goals including the tournament's first double hat-trick to help reigning World junior champions India crush Sri Lanka 17-1 in the Junior Asia Cup hockey tournament in Karachi on Thursday.

Sandeep continued with his immaculate conversion and scored almost at will as India secured their second comfortable victory, after the 10-0 rout of China, in their opening Group B game of the regional junior World Cup qualifying rounds.

In the only other match on Day three, defending Asian junior champions South Korea registered a convincing 5-0 win over Singapore.

Three top teams from the Asia Cup will qualify for next year's Junior World Cup in Amstelveen, The Netherlands.

India, who meet Bangladesh next on Saturday, bettered host Pakistan's 15-1 victory margin against Chiense Taipei.

Sandeep is now the tournament's top scorer with ten goals.

"I want to keep the momentum in the crucial matches and help India win this tournament," he said.

The lithe penalty corner expert scored in the very first minute and then added goals from penalty-corners in the 11th, 20th and 25th minutes as India romped to a 7-0 lead at half-time.

He then added three more in the 46th, 48th and 57th minutes to take over as leading scorer from Pakistan's Imran Warsi.

"It was again a fantastic show of penalty-corner conversion by the Indians. Scoring nine out of 17 penalty-corners is a good rate," said coach Harendra Singh.

Hari Prasad, Tushar Khandekar and captain Sandeep Michael scored a brace each while William Xalxo, Girish Pimpale, Nitin Kumar and Muthuselvan scored once each.

South Korea showed poor finishing in their match and could have scored a dozen had they availed the chances.

Jong Hyun and Sung Kweon Hong netted twice while Chang Yong scored one as Singapore resisted more than expected.

Hosts Pakistan opens the fourth day's action tomorrow in against Japan, Singapore faces Chinese Taipei, China plays Malaysia and Bangladesh takes on Sri Lanka.