Xintong becomes only the third player from Mainland China to reach the single table set up. The others of course Ding and Si

Seven-time champion Ronnie O'Sullivan is level at 4-4 with Zhao Xintong after an entertaining opening session to their World Championship semi-final.

China's Zhao, 28, a former UK champion who is competing as an amateur, showed few signs of nerves having reached the single table set-up for the first time, racing into a 2-0 lead with breaks of 60 and 62.

However, O'Sullivan, 49, appearing at this stage for the 14th time, clicked into gear and responded with three consecutive half centuries of his own as he took the next three frames to lead 3-2.

The players then traded frames, with Zhao breaking the right corner pocket potting the black while crafting an 86 to draw level at 4-4.

Williams wins the frame, now 14-11 in the semifinal against Judd Trump.

So Williams won 12 of the last 16 frames now 15-11 ahead.

Good stuff from Judd under pressure, an 104 break now 15-12 to Williams.

Another century this time for Mark Williams and it is 16-12 to him going into the mid-session interval.

Judd's back to within three frames of Mark Williams, 16-13.

Another century for Judd, now just 2 behind Mark, 16-14.

Mark Williams, aged 50, becomes the oldest man to ever reach the World Snooker Championship final.