Marco Fu completed a scrappy 13-9 win over Scottish qualifier Anthony McGill to become the first man into the World Championship quarter-finals.
Fu, the world number 14, resumed the final session 9-7 ahead after the pair shared eight frames in the morning.
And although McGill won the opener with a break of 97, the Hong Kong man rattled off four frames without reply to progress.
He will play either Ronnie O'Sullivan or Barry Hawkins in the last eight.
Fu fends off McGill fightback
One of the most entertaining moments of a forgettable match was provided by Fu, who left a big chalk mark on the Scot after accidentally poking him with a cue as he rushed to take a shot.
McGill joked that the incident at the start of the final session cost him the game, but described his display as "rubbish".
Fu was also far from happy with his performance, saying: "I didn't play very well at all in the first two sessions, but started to regain confidence in the final session.
"Hopefully I can play better as the tournament progresses and peak at the right time."
McGill, 25, trailed overnight but briefly found some of the fluent form that made him a surprise Crucible quarter-finalist last season to score three half-centuries and take a 6-5 lead.
But - despite not being at his best - Fu's delicate touch began to tell and he took four of the next five frames to take control.
Selby held by Baird
Earlier, qualifier Sam Baird came from behind four times to hold world number one Mark Selby to a 4-4 first-session draw.
Selby opened with a break of 50 and scored two further half-centuries, but he could not shake off the world number 59, who replicated the form from his first-round win over Michael White.
Baird, 27, scored fifties in every frame he won, including a 100 in the sixth, to ensure he goes into Saturday morning's session all square.
In the afternoon's other best-of-25 last-16 tie, two-time former finalist Ali Carter maintained his two-frame advantage over Scotland's Alan McManus.
Carter led 5-3 overnight but was unable to pull away from 45-year-old McManus, who has not trailed by more than two frames throughout. The match plays to a finish on Saturday morning with Carter 9-7 up.
Williams recovers from early wobbles
In the other evening match, two-time world champion Mark Williams overturned a 4-1 deficit in the first session to take a 10-6 lead over world number 28 Michael Holt.
The 41-year-old Welshman made a sloppy start and Holt, whose only previous second-round appearance in seven attempts came in 2005, took advantage by scoring three well-constructed half-centuries.
Williams managed to grind his way through the next three frames to draw level at 4-4 and he improved considerably in the evening.