Former champion Shaun Murphy needs three more frames to reach the quarter-finals of the Betfred World Snooker Championship after taking a 10-6 lead over Yan Bingtao.
Murphy led 6-2 after the opening session and moved further ahead with the aid of breaks of 88 and 68, raising the possibility of winning the match with a session to spare.
However, Yan stopped the rot with a century in the 11th frame and further breaks of 50, 64, 70 and 58 kept the Masters champion's hopes alive heading into Monday evening's final session.
That session will also see the conclusion of the match between Mark Selby and Mark Allen, with three-time champion Selby holding a 9-6 lead.
Breaks of 67, 72, 78 and 75 helped Allen halve his overnight deficit, but Selby – who made a break of 135 in the 10th frame – took the final frame of a session which was cut short due to the slow nature of play.
Earlier in the day, Judd Trump fought back to lead David Gilbert 5-3 in their last-16 clash.
Gilbert was the quickest player out of the blocks as he fired two centuries to take a two-frame advantage over Trump into the interval of the best-of-25 encounter.
But the world number one responded by winning four frames in a row, ending the opening session with his second century break.
Stuart Bingham and Jamie Jones were locked at 4-4 after their first session, Bingham moving into a 2-0 lead before Jones won four of the next five frames, including a break of 121.
Bingham, who won the title in 2015, then scored 61 in the final action of the session to draw level with his opponent.