Padraig Harrington fired a nine-under-par 62 to take command of the season-ending Charles Schwab Cup Championship in Phoenix.
The Dubliner holds a five-shot-lead at 21-under-par over Australian Steven Alker, with the pair also battling for the season-long title of the Charles Schwab Cup.
Alker led the Charles Schwab Cup by over 600,000 points heading into this week's final event, meaning a top-five finish will see him win the season-long trophy even if Harrington wins this weekend.
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Nevertheless it would be a huge individual event for Harrington to win on the Champions Tour and would be his fourth win of the season.
"You know, today was a good day," Harrington said after Saturday's round.
"I think I've been playing pretty solid all the way through and just waiting for a good day like today.
"So, yeah, game has been good and if your game is good, good things like that come to you. But I will say you've got to be very careful for what you want, because I did say at the start of the week I wanted a 72-holetournament. I would be better off with a 54, wouldn't I?"
Harrington will play with Alker again in the final group of the day.
Alker is a shot ahead of American Brian Gay, while Germany's Alex Cejka is a further shot back on 14-under-par, with South African Retief Goosen completing the top five on 13-under-par.
But Harrington said he is taking nothing for granted ahead of the final round.
He said: "I've always been a better chaser than leader. We'll go and see tomorrow what happens. I've certainly given myself a few options.
"You know, five ahead, so hopefully I'll go out there and play well and can wave at the crowds which if it doesn't happen that way, well, we'll have to dig deep and find another way of winning."
Harrington would scoop $440,000 for Charles Schwab Cup Championship but would also pocket $1,000,000 if simultaneously winning the season-long cup, which is contingent on Alker slipping down the leaderboard.
The likely alternative is that the Dubliner wins the season-ending event and also pockets the second prize of $500,000 for the Charles Schwab Cup.
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