Qualifier Liang Wenbo became the first Chinese to reach the quarterfinals of the world snooker championship in Sheffield, England, when he came through a tense deciding frame against Joe Swail to win 13-12 on Monday.

Leading 9-7 at the start of the final session, the 21-year-old moved to within a frame of victory at 12-8.

He then saw Swail reel off four frames in a row to level at 12-12. The Northern Ireland player looked on course to win in the final frame before a missed brown handed victory to Liang.

Liang, who is making his debut at The Crucible, will now face tournament favorite Ronnie O'Sullivan for a place in the last four.

He said he had struggled for consistency during the match.

"The first session was very good but in the second session I felt very nervous and played very tight. I think I played well in the final session but I did make mistakes," Liang conceded.

Swail was unhappy with the re-positioning of the yellow in the final frame following a foul shot, claiming that it had not been put in the correct place. Liang managed to hit the yellow at the second attempt, without the cue ball going off a cushion, after appearing to be snookered initially.

Liang insisted, however, that he had not been given an unfair advantage, saying: "The referee did the right thing because I misjudged the first shot."

Looking ahead to his match against twice world champion O'Sullivan, the Chinese youngster said: "I'll try my best and I think I have a chance."

O'Sullivan made a maximum 147 break, a record third in world championships, on his way to beating fellow Briton Mark Williams 13-7 earlier in the day.

Also, Stephen Maguire saw off the challenge of Australian Neil Robertson 13-7. The Scotsman will face Joe Perry, who beat Stuart Bingham 13-9, in the last eight.

In other quarterfinal match-ups, Stephen Hendry plays Ryan Day, the new Welsh No. 1, while Peter Ebdon, the 2002 champion, takes on Allister Carter, who emphatically eliminated the 2005 champion Shaun Murphy 13-4 in the previous round.

(Agencies via Shanghai Daily April 30, 2008)