Qualifier Liang Wenbo became the first Chinese to reach the quarterfinals of the snooker World Championship 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 Wenbo.

Wenbo, who is making his debut at The Crucible, will now face tournament favourite 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," Wenbo said.

Looking ahead to his match against twice World champion O'Sullivan, Wenbo 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.