In only the second Monday finish in the event’s history, Paul Dunne, a 22-year-old Irishman, heads into the final round on the Old Course tied for the lead with South African Oosthuizen and Australian Jason Day on 12-under-par 204.
Not since 1930, when the legendary Bobby Jones achieved the feat at Royal Liverpool, has an amateur won golf’s oldest major and, with a posse of major champions among 14 players separated by just three shots, Dunne is facing a tough task to rewrite the record books.
The Dubliner, however, certainly wasn’t playing down his chances after catapulting himself into contention after a flawless six-under-par 66 and neither Spieth, who is one off the lead, nor Oosthuizen were writing off his title hopes.
“I’m not surprised,” Spieth said of Dunne’s presence at the top of the leaderboard, where another amateur, American Jordan Niebrugge, is also in the top ten with a circuit to go. “There’s some great amateurs around these days and there will be an amateur that wins a PGA Tour event, probably even a major, at some point in the next decade or so.
“They’re just coming into events with no fear and I think it’s awesome. We certainly expect them [Dunne and Niebrugge] to make a run tomorrow and don’t consider them falling out of it at all.”
Oosthuizen, the last player to win an Open at St Andrews, was Dunne’s playing partner for the third round and his reply was emphatic when asked if the event’s surprise package could finish off the job. “Absolutely,” he said. “The way he played today, definitely. Everyone within three or four shots has got a really good chance of winning and it’s all about composure now and handling the pressure.
“Everyone playing for a major championship gets nervous, but for a lot of people that drives them to play even better. Tomorrow is going to be a tough day for Paul, but he’s played unbelievable so far.
“He hit a second shot at the 17th today that was one of the best I’ve ever seen. In fact, he made me nervous on my shot there because I was going the completely different route – low and running – and tugged it a bit to the left. His was an amazing shot.”
Dunne’s score was the lowest by an amateur on the Old Course in an Open Championship. It was one more than Englishman Tom Lewis shot when leading at Royal St George’s in 2011 but also equalled the second best score by a non-paid player in the event.
“It’s surreal that I’m leading the Open, but I can easily believe that I shot the three scores [69-69-66] I’ve shot here,” said Dunne, who raced to the turn in four-under 32 before picking up two more shots on the inward journey.
“If we were playing an amateur event here, I wouldn’t be too surprised by those scores. It’s just lucky that it happens to be in the biggest event in the world. Hopefully I can do it again tomorrow, but whether I do or not, I’ll survive either way.”
Oosthuizen and Day both shot 67s to sit alongside Dunne, but Spieth – bidding to become the first player since Ben Hogan in 1953 to win the season’s opening three majors – is lurking ominously a shot off the pace.
“At this point it’s free-rolling,” added Spieth of the opportunity he’s given himself after landing both the Masters and US Open already this year. “I want to win but, with a pretty bunched leaderboard, I’m going to have to play aggressive golf.”
Home challengers Marc Warren and Paul Lawrie start the final round five and six shots off the pace respectively after falling back following rounds of 72 and 74.