Ding Junhui was yesterday robbed by an unduly springy cushion of the chance to become the first player to make two maximum breaks in the same tournament.

The 19-year-old Chinese, already £35,000 in pocket from his 147 in his opening match of the Saga Masters, was ideally placed to repeat the feat in the fourth frame of his quarter-final against Stephen Lee until a positional shot unexpectedly bounced 18 inches past its intended destination. Ding managed to pot the awkward next red only to miss his 14th black.

Trailing 2-1 at the time, Ding's 105 break did, however, help guarantee him a further £32,000 as he went on to win five frames in a row and beat Lee 6-2 to reach today's semi-finals.

Lee's cagey approach meant it took 90 minutes for the Welsh Open champion to win two of the first three frames, but with a top break of the afternoon of only 31 he simply did not score heavily enough against Ding, who has already won three world-ranking titles in his short career.

From 2-1 down, Ding's 105 and then a break of 76 put him 3-2 ahead, which he stretched to 4-2 in the tightest of finishes to a sixth frame of 41 minutes.

Five times Lee attempted frame ball to level the match, but it was Ding at his fourth attempt who potted the black to open a two-frame gap. The Chinese player's fluency came to the fore in the next two frames as he recorded breaks of 98 and 80 to secure a semi-final place against Shaun Murphy or Stephen Hendry.

Ronnie O'Sullivan faces the 25-year-old Scotsman Stephen Maguire in this evening's semi-final.