Ronnie O`Sullivan crashed out of this year`s Royal London Watches Grand Prix after a shock defeat to teenage qualifier Judd Trump. `The Rocket` went down to a surprise 5-4 loss at the Scottish Exhibition and Conference Centre having let slip a 3-2 lead against his 19-year-old opponent from Bristol. Trump, the world number 41, might have easily crumbled playing in the first ranking quarter-final of his career, especially against the current world champion and world number one. But instead the youngster raised his game to clinch the "biggest win of my career" at this year`s Ј502,100 tournament. "I`ve not seen a lot of him, but he`s obviously dangerous," reflected O`Sullivan, who has complained about his poor form all week. "He`s a very good potter, but they`re all great potters these days, there`s a lot of dangerous opponents. "He`s young and he`s hungry for success, but I don`t what to say he`s great because he`s only young, he`s not been on the snooker scene that long. "You`ve got to give him another five, six or seven years before you start judging how good he is. "It`s only one performance at the end of the day, he needs to kick on and win the tournament for this win to really matter." On his own performance, the Chigwell cueman moaned: "I can`t pot a ball over six foot at the moment, I have to really struggle. I`m awful, but it still doesn`t stop me trying. "I feel more confident potting balls left-handed than I do right-handed at the moment." Trump edged 2-0 ahead before O`Sullivan hit back with breaks of 41, 66 and 104 for the lead. But Trump 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. "Ronnie`s probably the best player to have ever played the game. Beating him is massive, it`s bigger than beating anyone else," said Trump. "It feels brilliant to have beaten him, it`s the biggest win of my career by a mile. "We both struggled, but I went out there to win and I got the job done. "I had chances to win 5-3 and I didn`t take them, so I was glad I got another chance to win the match. "I know I`ve got the game to win it [the tournament], but I need to work on my break-building because I`m making 40 or 50 and then breaking down every frame. "I fancy beating anyone on my day, although I haven`t played that well to be honest."