Mickelson stooped over and grabbed his knees in disbelief.

The caddie, Billy Ciplinski out of the nearby golf club at Prestwick, was taken to a medical center at Royal Troon and then onto a hospital. And he likely will have the lead.

Add to the mix the last six winners at Royal Troon have all been American and it appears to enhance Johnson's chances along with those of compatriot and two-time major victor Jordan Spieth, who is not playing that well but still getting results. This is his first Open Championship since 2012, when he finished tied for 23rd. And not to be overlooked is Zach Johnson, the defending champion, who was 4 under through 10 holes. He had to scramble for par on the first hole and took bogey on the next hole.

So why the nerves?

After McIlroy's press conference Tuesday, Golf Channel analyst Brandel Chamblee said he believed McIlroy would regret those words for the rest of his life. He'd become the third-oldest major champion in history (behind Julius Boros at the 1968 PGA at age 48 and Jack Nicklaus at the 46 years old and 2 months). "I got into golf to win championships, and win major championships".

Doping is something the Royal & Ancient (R&A) takes seriously, because it strikes at the integrity of the sport, Martin Slumbers, the head of the organisation, said on the eve of The Open at Royal Troon.

Northern Irish superstar Rory McIlroy, who missed his 2014 title defence a year ago through injury, returned in style with a front-nine four-under 32, bettered only by Reed, Thomas and Australian Matt Jones.

McIlroy's chip ended up in a bunker, from where he escaped with a par, while Watson pitched to 10 feet and birdied.

Oosthuizen and Els have won three Opens between them‚ while Grace is turning into a consistently tough competitor in the Majors.

American Patrick Reed's decision to spend a week of reconnaissance at the Scottish Open yielded a handsome dividend as he sprinted to the top of the leaderboard early in the British Open on Thursday.

Thomas masterfully navigated the front nine with 5-under-par, hitting birdies on the first four holes and the seventh hole.

There were huge roars for a fine pitch at the sixth and a superb tee shot at the notorious "Postage Stamp" eighth hole, and even bigger cheers as he saved par from about 40 feet at the 13th.

Meanwhile, Rory McIlroy is now at 3-under-par through the seventh hole. He told me what club to hit, gave me all the information. It was a proud moment for the 53-year-old Scotsman but things soon were looking bleak after his 6:35 a.m. start.

He reached the turn in 33 and briefly led the championship before finishing with a respectable level-par 71.

"I feel like I'm hitting the ball well enough to have a good final three rounds and hopefully make a run at it. It would have been easy to score 78 there, simple".

The back nine was once described by Gary Player as, "the most hard in the world when the wind is blowing".