Jak Jones opened up a 13-10 lead over 2015 champion Stuart Bingham to take control of a shortened third session of their World Championship semi-final.
Resuming at 8-8, Bingham took the first frame of Saturday morning, but Welsh qualifier Jones responded with three half-century breaks as he reeled off five consecutive frames.
Bingham rallied with a superb 104 break, but the protracted nature of the 21st frame in particular - which lasted over 50 minutes and saw both players take toilet breaks - meant only seven of eight scheduled frames were completed.
Kyren Wilson holds a 14-10 lead over David Gilbert, with their last-four encounter concluding at 14:30 BST.
More to follow.