( L - R ) Martin Manley, Michael O'Hara - file

Seven Jamaicans advanced to the semi-finals of their events after the opening day of competition at the 15th World Junior Championships in Eugene, Oregon yesterday. Sprint hurdler Tyler Mason was the most impressive. He won heat two of the 110 metres hurdles in 13.46 seconds to be the third fastest qualifier.

"I am happy with the time, although I felt a bit sluggish coming out of the starting block, but I will be much faster in the semi-final," said Mason.

Despite winning his heat, Marvin Williams had to work hard to cross the line in 13.71, just edging out Francisco Lopez of Spain, 13.75. "I am not too pleased with my time but I hope to get it right in the semi-finals," said Williams.

Davd Omoregie (13.24) of Great Britain and Frenchman Wilheim Belocian (13.40 ) are the two fastest qualifiers.

Both Jevaughn Minzie and Michael O'Hara are through to this evening's 100m semi-finals.

Minzie clocked 10.32 seconds to win his heat , ahead of Josh Clarke of Australia who was second in 10.36.

"I wanted to be more relaxed qualifying, but after shutting it down a bit early I had to step it up in the latter stages as the Australian and the Japanese athletes were coming fast towards the end," said Minzie.

A slow starting O'Hara had to settle for second in his heat in 10.36, behind winner, Andre Azonwanna (10.30) of Canada.

"The starting block was a problem for me and because of this I got out a bit slow and I am not too pleased with the time and my execution. I was not in the right frame of mind as I did not want to compete in the 100m as I came here just to run the 200m, but I was told to run it (100m) and I had no choice," said O'Hara.

In the girls' 100m Jamaica's lone representative, Kedisha Dallas, also advanced. Dallas was second in heat one in 11.68. The heat was won by Poland's Ewa Swoboda in 11.42. The fastest semi-final qualifier was Britain's Dina Asher-Smith who clocked 11.18 to capture heat five.

Nathon Allen and Martin Manley are also in today's boys' 400 metres semifinals.

Allen, 48.06, was third in heat two, won in 47.06 by Japan's Kaisei Yui. Manley clocked 47.20 for second in heat four behind Bahrain's Abbas Abubakar, 46.92. The fastest qualifier was Japan's Nobuya Kato who captured heat three in 46.23 seconds.