Five Indian boxers won their preliminary bouts in the Asian Youth Boxing Championships in Tehran today. Former World Junior Championship bronze medallist Shiva Thapa led the charge. Thapa out punched Bobonazaro Suhrob of Uzbekistan 12-1 in 54kg in his opening bout. G Nagarjun in 57kg had it easy against Mahmoud Albadawi of Syria who retired due to injury in the third round of their bout. Harpal Singh notched up a 3-0 win over Mir Akyazlah Bin Azmi of Malaysia in the 64kg division, while Kishan Thapa 69kg defeated Pongrai of Thailand 8-1.Sumit Sangwan knocked out Nariddin Matkazimov of Kyrgyzstan in the third round in 75kg, while leading 8-3.