John Higgins came through a thrilling clash with Judd Trump to set up a Welsh Open quarter-final against Ronnie O'Sullivan.
The pair have won nine world titles between them and will go head to head in Newport after Higgins edged through 4-3 against Trump.
He led 2-0 after breaks of 66 and 63, and after Trump levelled at 2-2 the Scot edged ahead once more.
Higgins was unlucky not to win the match in frame six when, following a safety battle, Trump left the brown over the left corner pocket but covered by the pink.
It was the only ball Higgins, 17 ahead, required and he came off the right-hand cushion to pot it - but followed it in with the white and Trump cleared to force a decider.
Both players missed chances before Higgins ran the last red round three cushions and straight into the middle pocket to set up a frame-winning clearance.
Higgins told worldsnooker.com: "I have been losing those matches in recent years and when the cue ball went in off the brown, I was thinking, 'This is going to happen again'.
"You get good bits of luck and bad bits of luck. I played for that red in the decider, I knew it was on and looked at the angle."
O'Sullivan had an easier outing, beating Ricky Walden 4-1.
Walden was off-colour in the first two frames but the third was classic O'Sullivan, a 103 break taking him within a frame of victory.
Walden responded with 88 but the five-time world champion closed out the match with an 86.
Higgins' fellow Scot Stephen Maguire was on the wrong end of a 4-3 scoreline, beaten by Joel Walker despite making the only three breaks over 50.
Joe Perry beat Stuart Bingham by the same score, helped by breaks of 73, 51 and 69.
Mark Selby and Ding Junhui made straightforward progress, Selby beating Ali Carter 4-1 with breaks of 55, 64 and 81 while Ding cruised past Scottish youngster Scott Donaldson 4-0.
The Chinese star was dominant from the outset, Donaldson scoring just one point in the first two frames in the face of breaks of 128 and 86.
Selby will take on Perry while Ding faces Walker.
Home favourite Mark Williams could not follow up his superb win world number one over Neil Robertson, losing 4-2 to Marco Fu whose 103 break in frame five swung the match his way.
Fu will play Barry Hawkins, who came from 2-0 down to beat Liang Wenbo 4-2.