Three-time Open champion Gary Player says the winner of this year's championship will be the golfer who has the "right mind", not the man who drives the ball the furthest.
Colin Montgomerie also believed a strong mentality would help to determine which player would be holding the Claret Jug at the end of the day.
With 18 holes remaining at St Andrews, the leading 25 players are separated by just five strokes, setting up an enthralling closing round over the Old Course on Monday.
Looking ahead to the final round, Player told Sky Sports News HQ: "This is an exciting finish. Jason Day, who has a magnificent swing, has been knocking on the door in a lot of majors.
"It would be nice to see him win. It would also be nice to see amateur Paul Dunne win or Jordan Spieth win - there's a whole host of players it would be nice to see win.
"Today, the man with the right mind will win. Not long hitting, as everyone continually talks about."
And what advice would Player give Paul Dunne, the amateur who shares the lead after 54 holes?
Player, who turns 80 in November, added: "It's an outstanding achievement. It would be really exciting if he could win, because the last amateur to win The Open was Bobby Jones in 1930.
"Nobody expects him to win. He's got nothing to lose. But be aggressive. You'll not win by playing safe. Rip it at the flags and believe in yourself."
Montgomerie saluted the efforts of Dunne and said that "history was in the making".
The 52-year-old Scot told SSNHQ: “The competition is so tough these days and that makes it even more remarkable; let’s hope this young man can continue to handle himself as well as he has done so far. It will be a day to remember for the rest of his life no matter what happens.”
Another player who could make history on Monday is Spieth. The 21-year-old American is one stroke off the pace and if he could lift the Claret Jug, it would make him only the second golfer ever to win the Masters, US Open and Open in the same year.
Player said of Spieth: "He's refreshing. He speaks well. Always looks tidily dressed. He comes up with the right answers."
Montgomerie added: "You can only claim to be number one in the world if you are and Spieth isn’t at the moment, but the way he is going, Rory McIlroy has to be careful.
“He has the mental strength to do it and he speaks so well for such a young player. He is possibly favourite for the Open and it will be interesting to see how he handles it.”
And Player has stressed it would be good for golf if 14-time major winner Tiger Woods could rediscover his old form.
The American has not won one of the big four events for more than seven years and Player offered this advice: "Tiger needs to re-start from the beginning - mentally, physically and theoretically.
"He doesn't swing the club correctly. He's confused. He's had lessons from all these different pros and they have all given him something different to think about.
"He won the US Open by 15 shots (back in 2000) and the next week he's having a lesson and I don't understand it.
"If he had never had another lesson after winning the US Open, I guarantee you he'd have broken all records, would have gone done in history as the greatest player of all time. He'd have won at least 20-22-24 majors.
"It's actually very sad. But it can come right. He has to find someone who has been in the arena and understands the game, knows how to think - because it's not just about the swing.
"It can come right and I hope it does because we need him in the game.
"Golf has always been a white sport and I know when he came to South Africa all these wonderful young black kids came out to see their great hero.
"He inspired millions of people. We need him back for the good of the game."
Player won nine majors during his career: Masters (1961-74-78); US Open (1965); The Open (1959-68-74); PGA Championship (1962-72).