John Higgins opened up a slender 13-11 advantage over Shaun Murphy heading into the final session of their World Championship semi-final at the Crucible Theatre.
Four-time champion Higgins, who turns 51 later this month, had not led at the end of a session throughout the tournament but picked the ideal time to change that as he bids to reach a record-equalling ninth final in Sheffield.
Higgins, who started the day strongly but was repeatedly pegged back by 2005 winner Murphy, ended it in the same fashion as he compiled his first century of the contest to hold sway.
The concluding chapter of their best-of-33 encounter will begin on Saturday at 14:30 BST, with the winner playing either China's Wu Yize or Northern Ireland's Mark Allen in the final.
Having resumed at 8-8, England's Murphy struck the first blow on Friday evening with a break of 60 to move into the lead for the first time since the end of the seventh frame.
However, in keeping with what had gone before, Higgins immediately responded with runs of 44 and 55 and then pinched the following frame after laying a snooker on the brown.
A wonderful break of 82 from Murphy ensured the players could not be separated at the mid-session interval.
The duo then conjured up plenty of drama and some superb snooker as they traded the next two frames.
Higgins constructed a 63 and Murphy then knocked in a superb century from the Scot's break-off shot.
At that stage 12-12 looked the likely outcome to a session in which both players delivered performances brimming with resolve.
However, Higgins found an extra gear when it mattered, crafting a run of 70 and then signing off for the evening with a superb 101.
Higgins growing stronger - analysis
Seven-time world champion Stephen Hendry speaking on BBC Two:
It's what John Higgins has done in every match this championship - he's got better as each match has gone on and played his best snooker near the end of the match.
He knows when the business end of these games are and he just finds gears, that's what he's always done.
Former World Championship semi-finalist Joe Perry:
That's the best John Higgins has looked in this semi-final.
Since the interval that's breaks of 63, 70 and a century - clinical, one-frame snooker, that's what you want at this stage of the match.
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