U.S. OPEN : Foreign Invasion at Oakmont : Golf: South African Els is two-stroke leader over New Zealander Nobilo after shooting a third-round 66.

So what happened to bad, bad Oakmont?

The course that was supposed to be harder than the head of a sand wedge, golf’s final exam--well, it has been more like an open-book test for the best golfers in the world.

As for North American golfers, let’s just say they’re going to have to come from behind if they’re going to catch South African Ernie Els or New Zealander Frank Nobilo and win the U.S. Open today at pussycat Oakmont Country Club.

Els toured the front nine in a record-tying 30 on his way to a 66, a 72-hole total of seven-under-par 206, and a two-shot lead over Nobilo, who had a 68 on a day when the U.S. Open turned into what amounted to a foreign tourist attraction.

The closest Americans are Tom Watson, Hale Irwin and Loren Roberts, in a group at 209 with second-round leader Colin Montgomerie of Scotland, one shot behind Nobilo and three behind Els.

Watson rebounded from Friday’s 73 with a 68 and said he helped himself by practicing putting on the floor of his living room.

Watson said there are many with hopes of winning.

“I’d say anybody within even par will have a chance,” he said.

It might not be an American. There have been only three foreigners who have won the U.S. Open since 1927 and none in 13 years, but that might change today. At least Els hopes so.

“I feel pretty good, obviously,” he said. “What can I say?”

He didn’t need to say much Saturday at Oakmont, which gave up 182 birdies and four eagles to 65 golfers. For the third day in a row, the average score went down, from 75.2 to 73.42 to 73.40.

Next thing you know, they’re going to have to start limiting birdies. This isn’t what anybody expected at Oakmont, especially Watson, who had predicted more scores in the 90s than in the 60s.

Was he ever wrong. So far, there have been 30 scores in the 60s and none in the 90s.

Watson said the scoring has been good because the humidity has been high and kept the greens from drying out. So if you’re going to pin the blame, Watson said he knows where it should go.

“Mother nature,” he said.

Els needs to keep the ball in the fairway, make some putts and he might win his first major title.

On Saturday, Els, 24, had three birdies and an eagle on the first five holes. By then, he knew he was up to something special.

“I thought, ‘This is just happening for me,’ ” he said. “I was up there, you know.”

Els started at two under and took the lead from Montgomerie when the Scot bogeyed No. 5 and Els two-putted from 25 feet for birdie at No. 9.

Els slipped up on No. 10, when he three-putted after a weak chip and double-bogeyed, but Montgomerie fell back with four bogeys on the back nine.

“I’m still in it, sure,” Montgomerie said. “I’ve never backed away from a challenge.”

Nobilo is not exactly a household name in the United States, mainly because he has played one regular PGA Tour event in two years. But he is a fixture on the European tour.

With the chance to win his first major title, Nobilo said he is probably going to be nervous from the pressure.

“You are not human if you don’t feel it,” he said. “But I don’t get a chance to play in a U.S. Open every day, so I feel I have something to prove.

“Right now, that is the overriding factor. Maybe with three holes to go, it might be a different kettle of fish.”

Irwin’s 71 could have been better, but the three-time Open winner isn’t going to jump in a bunker and cover himself with sand.

It would have been an exceptional round if Irwin had a little more luck at No. 18. His hand slipped on his driver and he wound up with a double-bogey six.

At three strokes back, Irwin is in a familiar territory. He was four shots behind Mike Donald in the 1990 Open at Medinah, but tied him with a final-round 67 and won the playoff the next day.

Could it happen again?

“I’ve got to really play well,” he said. “It’s not that I’m that far behind; it’s that I’ve got that many more guys to go through to get there tomorrow.”

All it took for Roberts to leap into contention was to shoot 64 in a tidy round marked by seven birdie putts, the longest a 60-footer on the par-three 16th.

A 39-year-old from Memphis who went to Cal Poly San Luis Obispo, Roberts won the Nestle Invitational this year and tied for fifth at the Masters, but missed the cut last week at Westchester.

Roberts figures he might just have a chance today, based on what kind of temperament works at the Open.

“I always figured this is a good tournament for me,” he said. “I am a patient player, a monotonous player, you might say, methodical.”

Curtis Strange completed his third consecutive round of 70, which might be considered sort of monotonous if it weren’t so potentially rewarding. Strange is at 210 along with Steve Lowery, four shots behind Els.

Strange, who won the U.S. Open in 1988 and 1989, said he sees similarities.

“I’m playing as well as I did the second time that I won,” he said. “I’ve kind of moseyed along and done my business and hung in there, but I haven’t hit a good spell of four or five holes.

“Hopefully better later than never.”

Greg Norman, Steve Pate and John Cook are at 211. Norman’s 69 was his first sub-par round and couldn’t have come at a better time.

“I’m not thinking about tomorrow,” he said. “We’ll have to see the way (the leaders) finish. . . . If everybody says the same, 66 might be a good score to shoot.”

The way things are going at Oakmont, 66 might not be enough.

U.S. Open Notes

The cut was late in coming, but some big names didn’t escape it anyway. Lightning in the area Friday night forced postponement of the second round with 18 golfers on the course and that delayed the cut until Saturday morning. It turned out to be 147, five over par. Among those who didn’t make the cut were Nick Price, Nick Faldo, Larry Nelson, Lee Janzen, David Frost, Larry Mize, Payne Stewart, Jose Maria Olazabal, Corey Pavin and John Daly. . . . Rocco Mediate shot 79, then withdrew because of a bad back. Mediate was sidelined for four months before returning last week to play the Buick Classic.