The 30-year-old English shot-stopper has saved six of the nine spot-kicks he has faced since moving to Easter Road last summer. Now he is confident he can extend that incredible record should Hibs fail to see off the Bairns in open play at Hampden.
Williams told Press Association Sport: "If we go to penalties, people will be expecting me to save five out of five. So that type of record brings its own pressure. As a goalkeeper, penalties are your time to shine. Players are expected to score but if you save a couple then it's fantastic."
He added: "I've saved six out of nine this season. But my record of late hasn't been as good, I've let in my last two. But I back myself in these situations to do well and make saves. I will study as much as I can. Not just the top scorer, but all the players in the team. I also look into patterns and the psychology of it. But sometimes it can just come down to guess work."
The Edinburgh outfit - without a Scottish Cup triumph since 1902 - return to Glasgow's south side for the first time since their 5-1 mauling by city rivals Hearts in last season's final.
Former Crewe keeper Williams was still on the books of Colchester when the Leith side suffered that derby disaster but he revealed boss Pat Fenlon's new recruits are just as desperate to make up for the pain it caused as any of the Hibs players who were present for that nightmare.
He said: "We've not spoken about what went on that day - it's well-documented and everyone knows what happened. But we have spoken about the feeling that getting to a final and losing out gives you.
"We've got players in the squad that have won the Scottish Cup with other clubs and players who have come close. So we can learn from that. We know how that affects players and fans so now it is time to try and put that right.
"When I first moved up here, I was surprised when they told me a club the size of Hibs had gone 111 years without winning the cup.
"But we know that if we do win it, we will go down in the history of the club - we will become legends. All players would love that so that is a great motivating factor."
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