Arun Prakash Rajagoplan upset top seed Sun Yong Kim of Korea 6-4, 3-6, 6-4 to advance into the boys' singles semi-finals in the Hong Kong Open junior tennis championships on Thursday.

The 18-year-old Indian, who last week won the doubles title at the Grade A Osaka Mayor's Championship in Japan, defeated local lad Cheuk-Wai 'Jack' Hui 6-3, 6-3 in the pre-quarter-finals after knocking out Australian Alexander Petropoulos 7-6(7/3), 7-6(7/5) in the earlier round.

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Earlier, sixth seed Divij Sharan, Arun's winning partner in Japan, lost in the third round to a lower-ranked Austrian, Martin Fischer 6-4, 3-6, 4-6.

He beat Kazakhstan's Syrym Abdukhalikov 3-6, 6-0, 6-2 in the second round of the 64-player draw.

Divij and Arun also reached the doubles semi-finals, defeating the local pair of Gilbert Wong and Kwok-Yeung Ng 6-1, 6-4 in the second round and David Galic and Todd Ley of Australia 6-1 6-3 in the quarters.

In the 32-player draw in the girls' section, Gayatri, daughter of Davis Cup coach Ramesh Krishnan, came through two qualifying rounds but lost in the first round of the main draw to Wen-Hsin Hsu of Chinese Taipei 1-6, 1-6.

Gayatri, partnering Jodi Lo of Hong Kong, also lost in the doubles 0-6, 1-6 to Holland's Kelly De Beer and Veronika Chvojkova of the Czech Republic in the first round.