The 2000 and 2003 champion finished strongly to build a 10-7 advantage against old rival John Higgins as the pair prepare for one last push for another Crucible title on day two of the marathon best-of-35 battle.
Born just two months apart in 1975, Welshman Williams and Scotsman Higgins are contesting the first final between two forty-somethings since this once-nomadic tournament’s 1977 move to Sheffield.
Both survived tough semi-finals, with Higgins edging Kyren Wilson, while Williams fell over the line in a late-night nerve-jangler against Barry Hawkins and admitted to eating a kebab at 2.15 on Sunday morning.
Against most expectations Williams made a flying start to the final, leading 5-1. Higgins fought back to draw level at 7-7 after making three century breaks, runs of 119, 127 and 117, and momentum looked to have shifted to the Scot.
But Williams notched his first ton, a 118, in the 15th before pulling away for the second time in the day to set up a tantalising finale.
Higgins showed his mettle against Wilson and also overcame Judd Trump in a quarter-final final-frame decider. Such resilience could prove vital on Monday.
“You’d hope so. But it could go Pete Tong, I’m sure,” Higgins said. “It’s been proved in the quarters and the semi and it’d be great to have that back-up in the final.”
He was looking for a better outcome than last year when he surged 10-4 clear of Mark Selby and had the title in his sights before running out of steam.
Williams had crossed the line against Hawkins just moments before midnight on Saturday. His head was spinning, his game was in pieces, and Williams predicted Higgins would whitewash him in the final if they had to start immediately.
Thankfully for Williams it was an afternoon start but it was still less than 12 hours after his late-night takeaway snack that he was walking out for his fourth Crucible final.
“Hopefully if it goes close towards the end I won’t collapse like a cheap tent again,” said Williams.