World number four Ding Junhui took control in the second session against Ronnie O'Sullivan to lead 10-6 in their World Championship quarter-final.
The China number one, losing finalist at Sheffield's Crucible venue to Mark Selby last year, rattled off five frames in a row from 5-5 including a century clearance against the five-time world champion from England.
But O'Sullivan managed to hit back with a quick-fire century in the final frame of the evening to give himself some hope going into Wednesday's final afternoon session in the best-of-25 frame match.
Ding needs just three more frames of the possible nine to be played to reach his second successive semi-final while O'Sullivan has it all to do as he needs to win seven.
It was a high-quality encounter with a break of at least 50 in every frame in the morning session and that astonishing standard was repeated in the evening.
Ding, 30, has not beaten world number 12 O'Sullivan in a ranking event since 2006 but looks as if he could end the hoodoo and prevent the Englishman equalling Stephen Hendry's record of 12 Crucible semi-finals.
Ding had a 63 clearance to go 5-4 ahead which O'Sullivan matched to level.
Ding then fired in breaks of breaks of 64, 65, 120, 59 and 56 to go 10-5 up before O'Sullivan responded with a typically brisk 104.
In the morning session, Ding had raced into a 3-0 lead before O'Sullivan took the next three and they resumed in the evening locked at 4-4.
Ding won the opening frame courtesy of a 71 break and then followed that up with a magnificent 128 clearance.
Another run of 71 put him further ahead with O'Sullivan barely getting to the table.
But the 41-year-old hit back with a breaks of 63, 99 and 65 to level at 3-3.
Ding edged the next via a tense respotted black after the frame had finished tied, but O'Sullivan restored parity with a run of 59.
In the day's other quarter-finals, four-time world champion John Higgins was in complete control at 11-5 ahead of Kyren Wilson.
Hong Kong's eighth-ranked Marco Fu, another bidding to become Asia's first men's world champion, trails title-holder Selby 6-2 in their quarter-final.
And Barry Hawkins leads Stephen Maguire 5-3 after their opening session.