Matthew Stevens overcame a strong challenge from Joe Swail to win 10-5 and book a last 16 tie with Ken Doherty at the World Championship in Sheffield.
Stevens made the most of Swail's mistakes
Stevens, last year's runner-up, took a 6-3 lead into the final session, but Swail reduced that to 6-5, by winning the 10th and 11th with a 71 break.
A bad safety in the 12th allowed Stevens to steal in to make his third ton, before he took the 13th.
The 28-year-old then capitalised on two more Swail mistakes to wrap up the win.
On Monday, Stevens won five out of the first six frames, posting two breaks over 50 and then a century in the fourth to carve out a big lead.
His Northern Ireland opponent made 82 in the second before a scrappy seventh went his way to reduce the deficit to three.
Stevens recorded his second century in the next, although Swail bounced back with an 80 to take the final frame of the session.
M Stevens (Wal) 10-5 J Swail (NI)
74-26 (54) 42-82 (82) 76-52 106-0 (106) 69-18 58-5 40-56 103-1 (103) 22-80 (80) 27-65 51-79 (71) 120-14 (112) 54-49 72-3 72-64 (64 Swail)