Boskovic slotted home two minutes after the break in a game that saw both sides reduced to 10 men as the hosts were left to rue missed opportunities and now have it all to do in the return leg in Uzbekistan if they are to remain in this season's competition.

Chonburi started the game with a flourish, enjoying much of the early possession and striker Pipob On Mo was able to use his strength to weave his way past three defenders before forcing Murotjon Zukhurov into a save at his near post.

Midfielder Therdsak Chaiman then had a sight of goal from 15 yards out after quarter of an hour but Zukhurov smothered his effort.

Chances were hard to come by in the first-half as both sides cancelled each other out.

Sharks coach Withaya Laohakul switched things around in a bid to give his side more impetus by taking off Arthit Sunthornphit after 33 minutes for tall Brazilian striker Ney Fabiano.

But it was Nasaf who had the best chance of the opening period after 37 minutes when a long cross from the right flank saw Boskovic produce a bullet header from six yards out but keeper Sinthaweechai Hathairattanakool parried it away.

Nasaf's Erkin Baydullaev and Suttinun Phukhom of Chonburi were then given yellow cards for separate rash challenges in the 39th and 40th minutes as the first-half ended goalless.

It did not stay that way as Boskovic fired past the Chonburi keeper to give the visitors the lead two minutes into the second period.

Andrejs Pereplotkins then crossed for an unmarked Jahongir Jiyamuradov a few minutes later but he curled a shot just wide of the far post before Baydullaev and Suttinun again received yellow cards within a minute of each other for blatant fouls and both were sent off.

Nasaf were then content to sit back and protect their lead but Nosirbek Otakuziev wasted two clear chances on the counter-attack in the 79th and 80th minutes, the first due to poor control and the second he fired straight at Sinthaweechai.

Fabiano then poked the ball past the right post in the dying minutes as Chonburi were unable to find the equaliser they desperately needed.