Vijay Singh rolled back the years with a five-under 65 to put himself firmly in contention after the third round of the Honda Classic.
The 56-year-old Fijian is just one shot off the lead in a share of second place after carding the best round of the day at PGA National in Florida.
Rookie Wyndham Clark heads the leaderboard on seven-under 203 after firing a three-under 67 for the second successive round.
Singh, who claimed the last of his 34 PGA Tour wins - which include the 1999 Honda Classic - in 2008, rattled in four birdies in six holes from the third before making his only bogey at the ninth.
A solid back nine saw him add further birdies at the 15th and 18th to move to six under, where he was later joined by South Korea's Kyoung-Hoon Lee, who birdied the 18th for a 68, and American Keith Mitchell (70), whose bogey at the 16th cost him a share of the lead.
Singh will become the oldest winner in PGA Tour history - Sam Snead holds the current record after winning at the age of 52 in 1965 - if he prevails on Sunday.
Clark made a storming start and his putter was red hot as he made five birdies over the first seven holes to storm clear of the field at nine under before stuttering a little.
He made his first bogey of the day at the ninth and dropped further shots at the 13th and 15th, either side of a birdie at the 14th.
The 25-year-old was content with his round, though, and told Sky Sports: "It's what I dreamed about, what I played for, and I'm just super-pumped to finally have the chance to be in contention in a final group on Sunday.
"I felt really confident on the greens, I had good speed, I could see my lines and I just felt like as long as I gave myself chances I was going to make some.
"Realistically I shouldn't change a thing [on Sunday]. I've played the front very well and the back I've managed. I'm just going to continue hitting the same shots that we've been hitting, the same clubs off the tee and just hope the putts keep falling."
Rickie Fowler fancies his chances of mounting a final-round challenge after recording five birdies and just one bogey in a 66 to get to five under and in sole possession of fifth place after starting the day five off the pace, alongside Singh.
The 30-year-old, who won the tournament in 2017 and is seeking his sixth PGA Tour success, told Sky Sports: "It's a fine line out there with the greens. This golf course isn't playing easy, you are seeing scores aren't very low and we're still in single digits with the leaders, so I'm pleased with a 66.
"Tomorrow the wind's supposed to be up a little bit more, which I like. This place is a good test in the wind, if it's not already hard enough right now, so I think that plays into my favour being where I'm at.
"Some guys towards the top of the leaderboard haven't won yet and if I can go out and get off to a nice start, like I did today, it may not take that low a round to end up on top."
Brooks Koepka failed to get going as he trod water with a level-par 70, but the world No 4 is still handily-placed on four under.
He is tied for sixth place with fellow American Michael Thompson, who matched Fowler's 66, and first-round leader Jhonattan Vegas (69) among others.
Sergio Garcia signed for a second successive 70 to remain on three under and in a group of four tied for 12th place which also includes Lucas Glover (72), who slipped back after sharing the lead with Mitchell and Sungjae Kim overnight.
Im fared even worse than Glover with a seven-over 77 to tumble to one over and into a tie for 51st with England's Matt Wallace (72) among others.
Watch the final round of the Honda Classic live on Sky Sports from 6pm on Sunday.