Rory McIlroy suffered the embarrassment of being outscored by his marker in the third round of the Masters at Augusta National on Saturday.
As the last of 51 players to make the halfway cut on the mark of four over par on Friday evening, McIlroy was in the first group out this morning, with club member Jeff Knox alongside as a non-competing marker.
And Knox, who performed the same role for defending champion Bubba Watson last year, proceeded to show the two-time major winner exactly how to play the course, carding a two-under 70 to McIlroy's 71.
McIlroy had to birdie three of the last four holes to keep it that close - in match play he would have lost 4&3 - and said: "Jeff was a great player and beat me by one. I thought he was going to be nice and three-putt the last so we could have a nice half.
"I don't think I have ever seen anyone putt the greens as well. I was thinking of getting him to read some of mine. He looked like he should be playing in the Masters."
McIlroy got off to a good start with a two-putt birdie on the second, but his approach to the short third ran over the green and he was unable to get up and down for par, while birdie chances went begging on the fourth and sixth.
An errant tee shot led to another bogey on the seventh and an outward nine of 37 completed in 90 minutes, with Knox - who holds the course record of 61 from the members' tees - out in 35 after matching McIlroy's birdie on the second.
McIlroy dropped another shot on the 10th after missing the green left for the second day running, and smiled wryly when he missed for birdie on the 12th only to see Knox casually hole from 30 feet.
A visibly frustrated McIlroy drove into Rae's Creek on the left of the 13th and although he saved par after a penalty drop, another birdie putt catching the edge of the hole on the 14th and staying out summed up his day so far.
The 24-year-old two-putted the 15th for birdie and finally holed a long putt for another on the 17th, while a superb approach to four feet on the 18th ended the day on a high note.
McIlroy felt conditions would make it hard for the later starters to shoot low scores, but Ryder Cup team-mate Ian Poulter, Miguel Angel Jimenez and Gary Woodland were showing what was possible.
Jimenez went to the turn in 34 and birdied the 10th, 11th, 13th and 14th, with a bogey on the 12th his only blemish, while Poulter had carded four birdies and a bogey on the front nine before a birdie on the 10th took him alongside Jimenez on two under.
Woodland's front nine was even more spectacular, four birdies and an eagle seeing him equal the lowest front nine in Masters history of 30 shots, previously achieved by Johnny Miller, KJ Choi, Greg Norman and Phil Mickelson.
When he also holed from two feet for birdie at the 10th the course record of 63 - held by Norman and Nick Price - or even the first sub-63 round in major championship history was in his sights, only for the 29-year-old to bogey the 11th and double-bogey the 12th.