Turnberry turned from a pussycat into a beast today but, while Tiger Woods became its biggest victim, Tom Watson continued magically on his merry way.

Birdies at the 16th and 17th came too late to save world number one Woods from missing only his second halfway cut in 49 majors as a professional and his first in the Open Championship.

But just before the three-time winner made his shock exit - a horror run of seven dropped shots in six holes around the turn did the damage in a 74 - 59-year-old five-time champion Watson unbelievably sank 60-foot birdie putts on both the 16th and 18th greens.

And with the second of those he joined little-known fellow American Steve Marino out in front on five under par at the halfway stage.

In the wind and rain Watson, back on the course where he won his 'Duel in the Sun' with Jack Nicklaus in 1977, added a level-par 70 to his opening 65 and is thought to be the oldest player ever to lead a major.

Sam Snead was 54 when he held top spot halfway through the 1966 US PGA Championship.

"I would not be here if I didn't think I could win," said Watson before comparing himself to "another old fart", namely Greg Norman, who at 53 led with nine holes to go at Birkdale last July.

"I said yesterday that the spirits are with me. They keep me focused on the game plan.

"I guess the memories are with me, all the wonderful memories I've had playing links golf.

"To be able to be doing what I'm doing, that's pretty cool at age 59."

In September he will be 60.

Woods reflected: "I just played three holes very poorly. I was right where I wanted to be and bogey-bogey-double (at eight, nine and 10) got it going the wrong way.

"It's frustrating. I was playing well the first seven holes and was right there in the championship."

Watson is playing his 32nd Open. Marino is playing his first - but that did not stop Ben Curtis winning at Sandwich six years ago or Watson at Carnoustie in 1975.

The 29-year-old is on his first-ever trip to Britain and a week ago he was not even in the field.

He has never won a US Tour title, but was in a play-off in May, stands 77th in the world and is a star in the making according to 1989 winner Mark Calcavecchia, who lies just a stroke behind.

"He really doesn't have any weaknesses that I've seen," said 49-year-old Calcavecchia, like Watson trying to become the oldest major winner in history.

"He's a great kid and has got a ton of talent. He's going to win soon and it may even be this week."

Just getting to Scotland was an adventure for Marino, whose 20-foot eagle putt on the long 17th helped him to a two-under 68 - as, of course, did holing a 116-yard wedge at the third and sinking a bunker shot three holes later.

Originally third reserve, he was playing in Illinois last week when he moved up two spots, but did not have his passport with him and so asked his father - a missile defence engineer - to fly from Virginia to Florida to pick it up and send it to him.

Then, just before crossing the Atlantic, he was told that Japan's Shingo Katayama had pulled out with a back injury and he would be playing his first Open.

"They have links courses in the States, but it's not like it is over here," said Marino, whose early pro career included a 13-under-par 59 in a mini-tour event in Arizona.

"I'm just having a blast. It's awesome.

"I love the challenge that it presents. You have to drive it straight and, most importantly, you have to stay patient and stay positive.

"Once you start getting down on yourself and thinking negatively it will go bad real quick."

Padraig Harrington, after early exits from his last five Tour events, was facing the possibility of another when he stood four over with five to play, but the Dubliner parred the next three, birdied the 17th and made his four on the last to make sure he survived.

He may be eight back, but the first hat-trick of Claret Jugs since Peter Thomson in 1956 cannot yet be ruled out.

First-round leader Miguel Angel Jimenez could add only a 73 to his 64, but England's Ross Fisher, whose wife could go into labour at any time, improved to the same three-under total with a 68.

In the clubhouse alongside them are major winners Retief Goosen and Vijay Singh and Japan's Kenichi Kuboya.

Meanwhile, 16-year-old Italian Matteo Manassero, as well as having the thrill of watching Watson, guaranteed himself the silver medal as leading amateur.

Only two were in the 156-strong field and while German Stephan Gross, the European champion, could do no better than nine over, British champion Manassero shot a superb 70 to be one over and safely through.