LONDON, Oct. 17 (Xinhua) -- World champion Ronnie O'Sullivan was upset by teenager qualifier Judd Trump at the British Grand Prix in Manchester, losing 5-4 in the quarterfinals on Friday.

    Trump, the world 41 and aged just 19, was 3-2 down at one stage against the world number one before he launched a memorable comeback.

    "There are a lot of dangerous opponents. He's young and he's hungry for success," said the snooker Rocket.

    Trump edged 2-0 ahead before O'Sullivan hit back with breaks of41, 66 and 104 for the lead. But the English teenager pinched the next frame on the final pink to draw level.

    The next two frames were shared, before Trump booked his place in the semi-finals after O'Sullivan missed a difficult red to a middle pocket.

    Ali Carter, last season's beaten world championship finalist, beat four-time Grand Prix winner Steve Davis 5-3 thanks to breaks of 99 and 90.