Less than 24 hours after firing a brilliant 147 maximum break in his second-round win over Mark Williams, Ronnie O'Sullivan was back in action on the same table but soon found himself 2-0 down to debutant Liang Wenbo.
O'Sullivan failed to pot a single ball as Liang, who beat Joe Swail 13-12 in a thrilling clash late , compiled breaks of 80, 48 and 49 to keep the two-time world champion sat in his chair.
However, the Rocket hit back with breaks of 109, 58 and 71 to lead 3-2 before a missed red on a break of 24 proved costly, Liang clearing up with 104 to level the scores.
Liang, who accounted for 1997 champion Ken Doherty in the first round, edged back in front with a run of 89 but O'Sullivan took the final frame of the session to ensure the match was evenly poised ahead of tomorrow's conclusion.
Stephen Maguire came back from four frames down to level his quarter-final with Joe Perry at four frames apiece.
A major shock was brewing as Perry stormed into a 4-0 lead over the in-form Scot having rattled in breaks of 68, 121 and 82.
Maguire, who the China Open at the end of March, had led 8-0 and 9-0 in his first and second round matches respectively but managed just 20 points in the first three frames.
Maguire had stopped the rot against Perry with breaks of 54 and 91 to reduce the deficit to 4-2 while he also won the final two frames of session to leave the match all-square.