Paul Casey put himself in a strong position to claim his first Major Championship title with a composed 68 on day three of the 2020 US PGA Championship but he will have to see off third round leader Dustin Johnson on Sunday if he is to break his duck.
The top 17 names on the leaderboard are separated by just four shots ahead of what promises to be a thrilling conclusion to the first Major in 13 months.
Casey made his maiden Major appearance at The Open Championship in 2002 and has been a regular at the sport's biggest events ever since but his best finish was tied third at The Open in 2010.
The Englishman carded three birdies and a single bogey on his front nine on Saturday before parring every hole coming down the stretch to sit two shots behind 2016 U.S. Open Championship winner Johnson heading into the final round.
That left Casey in a tie for fourth on seven under par alongside two time defending champion Brooks Koepka and US PGA debutant Collin Morikawa, while Americans Cameron Champ and Scottie Scheffler were one shot better off in joint second.
Casey's countrymen Justin Rose and Tommy Fleetwood were just behind him in the big group on six under, while halfway leader Li Haotong finished the day another shot further back.
An extremely bunched leaderboard was changing all the time on a breathless and entertaining Moving Day, but Li managed to hold off his challengers and cling on to top spot with a patient and professional front nine performance before an unfortunate double bogey on the 13th saw him slip backwards.
After turning in 34, American Johnson made four birdies on the back nine to open up a one shot lead.
Casey, who has spoken this week about the positive difference the return of his caddie has made to his game, began his third round three shots off the lead and carded his first birdie of the day from seven feet at the fifth before giving the shot back at the next.
The 43-year-old holed his bunker shot at the short eighth for a birdie two before picking up another shot at the difficult ninth hole.
That saw him grab a share of the lead on seven under, but as he settled for nine pars on the back nine in windy conditions at TPC Harding Park, his rivals were able to move above him and he finished the day two shots adrift of Johnson.
Casey is particularly looking forward to doing battle with talented youngsters Morikawa, Champ and Scheffler on Sunday.
"I find it exciting," said Casey. "It's really cool. I'm probably considered a veteran now, which I don't mind if I am.
"I'm 43 and playing against guys in their 20s, early 20s, barely in their 20s, I relish that challenge.
"We have Morikawa and Champ, and Scottie is up there. Watching guys like Morikawa, phenomenal talents, and I relish the opportunity to go up against them.
"They probably weren't watching me, growing up. They were watching Tiger (Woods) or Phil (Mickelson) or whoever their favourite player was, but they probably saw my name on leaderboards occasionally, so it's nice I'm still hanging around out here with a chance to beat them."
After signing for a 65 that contained eight birdies, one bogey and a double bogey on Saturday, Johnson said: "I've been in contention a lot, and I've got it done a lot of times.
"Tomorrow is no different. I'm going to have to play good golf if I want to win. It's simple. I've got to hit a lot of fairways and a lot of greens.
"If I can do that tomorrow, I'm going to have a good chance coming down the stretch on the back nine."
Rose started his third round with two bogeys before following up a birdie at the fourth with another dropped shot on the next, but caught fire around the turn to burst into contention.
The 2013 U.S. Open winner holed his lengthy birdie putt at the short eighth before making further gains at the tenth and 11th to move to seven under.
He made another bogey on the 15th but parred his way home to remain in the hunt.
Olympic champion Rose said: "I worked hard to stay in it and obviously have a legitimate chance tomorrow.
"I'm going to have that freedom to go out there and play a few groups ahead and just see if I can find my round where I can kind of get it all together.
"I've sort of had good patches, but I haven't really had a lot of confidence in the game yet this week, so I've done a great job of giving myself a look. I'm looking for that one round - I'm looking for my round of the week.
"The last three Majors I played, they seem a lifetime ago but it was Pebble Beach, I think The Open, and then here. So I've been in the last few groups in the last three Majors.
"You have to keep knocking on the door. Like I said, if you are knocking on the door, more often than not you do find that round that you need on a Sunday.
"That's when the door opens. You never quite know when that's going to happen."
Fleetwood was playing in the day's final pairing alongside Li but made two bogeys and no birdies in his first ten holes to fall off the pace.
He bounced back with brilliant birdies at the 16th and 18th to head into Sunday with a spring in his step as, like Casey, he goes in search of a maiden Major title.
