ST. ANDREWS, Scotland — A remarkable third round of the British Open saw 22-year-old amateur Paul Dunne claim a share of the lead alongside Louis Oosthuizen and Australian Jason Day. Jordan Spieth was a stroke behind the leaders with a shot at his third consecutive major tournament victory.
Spieth's 66 left him in fourth place at St. Andrews. On Monday he will have a real chance of becoming the second man — after Ben Hogan in 1953 — to win the Masters, U.S. Open and British Open titles in the same year.
Spieth could yet be denied by Dunne, who is 80th in the amateur world rankings.
Dunne, from Ireland, showed admirable levels of composure to raise hope of a first winner of The Open Championship since Bobby Jones lifted the claret jug for a third time in 1930.
A recent graduate from the University of Alabama-Birmingham, Dunne missed the cut on his 2014 Open debut. But he was terrific all week, including consecutive rounds of 66. Then on Sunday, Dunne matched Spieth's 6-under score with a bogey-free round. His 54-hole total of 204 broke the Open's amateur record, 210 set by Iain Pyman in 1993.
Dunne was joined at 12 under by Day — a regular major challenger yet to claim a major — and Oosthuizen, trying to follow up his victory at St. Andrews in 2010. Both Day and Oosthuizen shot 67.
Two-time Open champion Padraig Harrington moved to 10 under with a 65. Marc Leishman carded a 64, the lowest round of the week, and was among nine players three off the lead. They include Sergio Garcia, Justin Rose and Adam Scott.
The third-round final pairing, Dustin Johnson and Danny Willett, failed to capitalize on Sunday's benign conditions that were in contrast to those that forced the final two rounds to be pushed back a day.
Johnson had one birdie and bogeyed the final three holes en route to a 75 that left him five behind. Willett reached 12 under through 10 holes, only to fall back with three dropped shots thereafter.
After finishing his second round five behind Johnson, Spieth suggested he would require "something like 10 under in the last two rounds" to give himself a chance of victory.
And he again demonstrated his ability to respond to setbacks. After his only Sunday bogey at the ninth, Spieth handled the trickier back nine in 32 strokes — thanks largely to three birdies in succession from the 10th.
If Spieth's charge was impressive, Dunne provided an even bigger thrill. Dunne took the outright lead for the first time on the 10th with his fifth birdie of the round and then mixed seven pars with a birdie at the 15th.
Day started with four straight pars, but soon clicked into gear. Oosthuizen birdied three of the last five to make it a three-way tie at the top.
Oosthuizen won by seven strokes on the Old Course five years ago. A much tighter battle can be anticipated on Monday, finishing day for the second time in Open history.