Mark Selby rewrote the record books as he became the first man to make six century breaks in a single World Championship match.
Selby was in sparkling form against Stephen Hendry as he closed in on a place in the Betfred.com World Snooker Championship quarter-finals.
After the first session on Saturday Selby led 7-1 and had made breaks of 125, 108 and 129.
He continued his domination as he made 100 in the first frame of the day and then followed it up with 127 in the 11th and 117 in the 15th frame.
Selby had chances to extend the record further as he made a break of 98 in the fourth frame and 87 in the 12th.
Seven-time World Champion Hendry, who had hinted this could be his last ever match at the Crucible, won two consecutive frames to reduce the deficit to 10-4 but Selby took the next to make it 11-4.
The last frame of the day showed Selby's confidence as he needed four snookers but still played on, got the required snookers and stole the frame by one point. Selby leads 12-4 and needs one more for victory.
On the other table, Shaun Murphy fought back to keep his hopes alive against Ronnie O'Sullivan.
The Rocket had a 6-2 advantage after the first session, but Murphy won three of the first four frames on Sunday.
O'Sullivan made breaks of 95 and 59 to take the 13th and 14th, before Murphy claimed the 15th and 16th frames but still trailed 9-7.
Ball by ball scoring and results from tournaments