FARMINGDALE, N.Y. - The contestants in the U.S. Open have had to be skilled this week at waking up and knowing the day of the week, what number round they're playing, and the hole they last finished before leaving Bethpage Black for the night.

For the fourth straight day yesterday, the competition was halted because of the weather or the setting sun in the middle of a round, leaving the vocal crowds wondering just where everything stands, and the players questioning where they are.

"It feels like Groundhog Day," West Chester's Sean O'Hair said. "It's the same day over and over and over again. There's not much that anybody can do about it."

Still without rhythm or flow, the soggy 109th national championship moves into Day 5 today with 60 players needing to go anywhere from eight to 17 holes to post a score for the regulation 72, only the third time in history the Open has gone into an extra day without a playoff.

The last twosome of Ricky Barnes and Lucas Glover has 161/2 holes remaining, with the two men tied for the lead at 7 under. They opted not to hit their second shots at No. 2 after the horn sounded to signal the stoppage of play at 7:58 p.m. because of darkness.

Play resumes at 9 a.m. today. If a tie results, an 18-hole playoff is scheduled to begin in the afternoon, provided that U.S. Golf Association officials believe they can complete 18 before the end of the day.

What may make today a riveting one - if weather doesn't interfere, with a 20 percent chance of showers in the morning and 30 percent in the afternoon - is those players stacked up behind the untested duo of Barnes, a PGA Tour rookie, and Glover, a one-time winner in six tour seasons.

Phil Mickelson, who curled in a 40-foot birdie putt at the 18th to end his third round to wild applause with a 69, was in a tie for third at 2-under par with the rejuvenated David Duval, 2008 U.S. Ryder Cup member Hunter Mahan, and England's Ross Fisher.

All but Fisher finished two holes of their final round; Fisher will complete No. 2 this morning.

"There's only two people ahead of me," said Mickelson, winner of three majors in his career, "and I feel like if I can get a hot round going, I can make up the difference."

After Mike Weir at 1 under came a five-player group at even par led by Tiger Woods, whose last stroke of the evening was a 12-foot birdie putt at No. 7. Woods may not have enough holes left to be a threat, but he won't be ignored.

O'Hair closed the day on a sour note, making a double bogey at the par-5 fourth to slip to 1 over and in a six-way tie for 13th.

Barnes, the 2002 U.S. Amateur champion, was the focus of the third round, which was played under an overcast sky with a couple of splashes of light rain. He shot an even-par 70 for a 54-hole score of 8-under 202, the second-lowest stroke total ever in an Open, and a 1-stroke lead over Glover.

Barnes went from a 1-stroke lead at the start of the round to 6 at the midway point. After an eagle at the par-5 fourth, he got to 11 under, only the fourth time in U.S. Open history that a player had gotten to 10 under par or better.

But Barnes retreated after a three-putt bogey at the long, par-4 12th and finished where he began - at 8 under.

"I knew it was going to be wet and tough, and I knew my nerves would be tested," Barnes said. "I wouldn't have liked to bogey the last hole and end it that way. But I've got to go back, take my shoes off and think, 'Hey, I shot even par [in the third round] with the lead.' "

Barnes lost his lead on the opening hole of the final round, hitting his tee shot in the rough and making bogey while Glover parred the hole.

Duval, with a 70, and Fisher (69) were tied for third at 207 after three, a shot ahead of Mickelson, Mahan (68), and Weir (74). O'Hair, who had a 71, was in a four-way tie at 209.

For Duval, once the top-ranked golfer in the world who is now ranked No. 882, it's a nice ride he hopes to finish today in a positive way.

"I've been there before," he said. "It's not like a distant memory . . . but I think the benefit I have is . . . I know what awful golf is about, too. I'm probably going to hit a lot of good shots in the next round and hit a couple of squirrelly ones, too, but I feel comfortable in what I'm doing and confident in what I'm doing, and that's all you can ask for."

Contact staff writer Joe Juliano at 215-854-4494 or jjuliano@phillynews.com.