China's Ding Junhui racked up a record-equalling number of centuries by a single player in a world championship match on Friday with his sixth helping him to a 14-10 lead over Alan McManus in the semi-finals.
The 29-year-old Ding hit his fifth ton on the way to a 9-3 advantage over Scot McManus, who responded with his second and third centuries to win five frames and get back to 9-8 at the Crucible Theatre in Sheffield.
World number 17 Ding finished the evening session in control but saw the chance of a 147 break disappear in the 20th frame when he missed a black on 113 after struggling for position.
The pair's combined total of nine centuries was a record for a world championship match, one more than the previous mark.
In the afternoon session, Hong Kong's 38-year-old world number 14 Marco Fu had come from 5-3 down to draw level at 8-8 with England's 2014 champion Mark Selby in the other semi.
Fu, who last reached the semis in 2006, was shocked to see his tip fly off while he was chalking his cue, having tied the score at 7-7 after two centuries in a three-frame streak.
He lost his tip when his score was on 33 in frame 15 but it was glued back on during a 10-minute suspension and he returned to complete a break of 81 and take an 8-7 lead.
Former world number one Ding's six centuries matched Ronnie O'Sullivan's against Barry Hawkins in the 2013 final and Mark Selby's versus Stephen Hendry in the second round in 2011.
He is aiming to become the first Asian player to reach the final but world number 29 McManus, at 45 the oldest player to reach the last four since Ray Reardon in 1985, is putting up a fight.
Fu and world number one Selby resume at 1000 local time (0900 GMT) on Saturday in the best-of-33 frame contest, while Ding and McManus play their final session at 1430 local.