SHEFFIELD – Chinese star Ding Junhui was trailing England's fast rising snooker player Judd Trump 5-3 after the first session of their best of 33 frames world championship semifinal on Thursday.

Ding, the first Chinese player to reach the last four in Sheffield, had got off to a superb start putting together a break of 102 to go 1-0 up but 21-year-old Trump, an 80/1 outsider prior to the tournament, levelled with a century break of his own.

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Trump - who ousted 2010 champion Neil Robertson in the first round - then built up a 3-1 lead and although Ding fought back to win the next two frames, the Englishman took the last frame of the session to hold a narrow overnight lead.

However, Trump, who signalled he could be a dark horse in the championships when he won the China Open, said he feared 24-year-old Ding - ranked number four in the world - was a very dangerous customer.

"I think he's starting to play his best now," said Trump, who is competing here for only the second time.

"He's never really played that well at the Crucible up till this year. But I still think he's got a lot to give in the tournament.

"He could easily run away with it if he starts to play well," added Trump, who has soared to 14 in the world rankings for next season.

The other semi-final saw Wales's two-time champion Mark Williams lead Scotland's triple world champion John Higgins 5-3 at the end of their first session.

Higgins, who will be replaced as world number one for next season by 36-year-old Williams whatever the outcome of the match, put together the only two century breaks of the opening session of 135 and 120 but the Welshman played the more solidly to hold a deserved lead.

For Higgins, who was at the nadir of his fortunes this time last year as he was provisionally suspended over matchfixing allegations of which he was later cleared, the whole experience is not getting any easier.

"It's (the championships) a test of everything," he admitted. "It's a test of whether you can get your sleep at night. Your whole nervous system is in meltdown for 17 days, it's just how you handle it."

"Experience only gets you so far, you've got to have the ability to go with it. You look at Judd Trump who's got no experience here and he is blitzing everyone."

The final begins on Sunday.