BANGKOK, July 17: Defensive errors cost India dear as they went down to Thailand by two second half goals in the first leg of the pre-Olympic Asia Group 9 football Qualifier at Suphan Buri near here today.India, who were looking for atleast a draw, held on gamely in the first half but were outplayed by their nippy rivals after change of ends.Bamruang Boonprom put the hosts ahead three minutes into the second half and Nirut Surasiang made it 2-0 in the 76th minutes and the score stayed that way till the end with Indian forwards messing up a few chances towards the fag end.India had a golden chance to reduce the margin 10 minutes from the end, but forward Bijen Singh shot wide from the top of the box with the defence in disarray and the goalkeeper out of position.An away goal would have counted for two which would have put India at a big advantage hosting the Thais in the second leg to be held in Calcutta on July 24.The Indian tactics against the speedy Thais seemed to work well early on as coachPK Banerjee's defensive tactics enabled them end the first half goalless. But the superior hosts stepped up pace and rattled the Indian defence with a series of long passes and quick release of the ball.Boonprom struck the first goal off a superb cross from A Puttan, who made a fine run down the right flank to catch the Indian defence off guard.Nirut Surasiang then put the hosts 2-0 up when defender Falguni Dutta made a horrendous mistake in making a clearance inside the box.Dutta tried to clear but completely missed the ball and the tall mid-fielder unleashed a powerful shot that swerved and completely beat an out-of-position goalkeeper Kalyan Chaubey to enter the net.Thailand strategy to go all out in the second half worked very well as India, playing in their 32nd Olympic qualifying game, totally lost their grip in the mid-field.India will rue their missed opportunity as the group had been reduced to two countries following the withdrawal of Singapore, Brunei and Laos.