Jordan Spieth's bid for the third leg of an unprecedented calendar grand slam remained very much on track in The 144th Open Championship at St Andrews.
Torrential rain on Friday and winds gusting up to 45 miles per hour on Saturday meant the tournament would finish on Monday for just the second time, but conditions were almost perfect for Sunday's delayed third round.
And Spieth was among those taking advantage to chase down overnight leader Dustin Johnson, who could only manage four pars to start his round on the defenceless Old Course.
Starting the day five off the lead, Spieth made the ideal start with a birdie at the first and also picked up shots on the fifth and seventh, before reacting angrily to a bogey on the ninth.
The 21 year old Masters Tournament and US Open champion produced the perfect response however, carding a hat-trick of birdies from the tenth to join Johnson and 2010 Open Champion Louis Oosthuizen in the lead on ten under par.
Australia's Marc Leishman had set the clubhouse target after a flawless 64, but another nine players were nine under par on the course on an extremely crowded leaderboard.
They included three-time Major winner Padraig Harrington, Irish amateur Paul Dunne, and Scotland's 1999 winner Paul Lawrie, with Eddie Pepperell in the clubhouse on eight under despite hitting his drive into the Old Course Hotel on the 17th to run up a double bogey.
Leishman had earlier needed to play the last three holes in two under to shoot the first 62 in Major Championship history - there have been 26 rounds of 63 - but the 31 year old narrowly missed good chances on the 16th and 17th before his approach to the 18th span back into the Valley of Sin.
Dunne was in the second group out on Thursday morning and birdied the first two holes, joking afterwards he wondered if someone had taken a picture of the scoring computer as proof he had led The Open.
And after birdies on the tenth and 11th the 22 year old amazingly held the outright lead once more, one shot ahead of Spieth, Harrington, Willett, Johnson and Australian Steven Bowditch.
The last amateur to win The Open was the legendary Bobby Jones in 1930, while Justin Rose was fourth at Birkdale in 1998 and Chris Wood fifth ten years later at the same venue.
Dressed in the same clothing, Dunne was asked for autographs by fans mistaking him for Spieth earlier this week and the pair were tied at the top of the leaderboard when the World Number Two holed from five feet on the 15th.
Harrington was unable to birdie 18th, but a flawless 65 set the new clubhouse target on ten under, with Retief Goosen and Jason Day joining Willett on that score as Johnson dropped back to nine under with a clumsy bogey on the seventh.
