Defending champion Ronnie O'Sullivan trails Joe Perry by two frames going into the final session of the second round clash.
The pair shared the eight frames of yesterday's absorbing session as world number 15 Perry moved from a 5-3 first session advantage to a 9-7 lead.
The damage could have been worse for O'Sullivan, with Perry missing a number of opportunities for a four-frame lead.
The five-time world champion made a statement of intent from the start of yesterday's session, compiling a break of 93 in the opening frame, only denied a century by going in-off on the black.
Perry restored his two-frame advantage with a break of 68 and went further ahead with runs of 48 and 46 in the 11th frame.
A missed red let O'Sullivan in for a break of 66 as he narrowed the gap to 7-5, and the Rocket got the better of a safety exchange to move within one frame.
Perry responded with two flawless back-to-back frames, a nerveless 86 restoring his two-frame advantage and a 73 moving him further ahead.
Despite his superb performance, Perry will have been disappointed not to hold a 10-6 lead overnight, with O'Sullivan bringing an end to a lengthy frame and an engrossing session by clearing from yellow to pink.
Alan McManus moved 4-3 ahead of fellow veteran Ken Doherty after a gruelling first session of their second round clash.
Scottish 43-year-old McManus compiled his first Crucible century in nine years – coincidentally the last was also against 44-year-old Dubliner Doherty – as he established a 4-1 lead.
But despite struggling to find any semblance of the form that brought him the 1997 world title, Doherty clawed his way back before the session was abridged with seven frames played.
Antrim's Mark Allen starts his second round match against Neil Robertson in the £1.25million event tomorrow.
Australian ace Robertson, the 2010 world champion, said: "Mark Allen is as tough an opponent as you could get in the last 16."