A very good day for Aussie Jason Day at Nelson

IRVING, Texas (AP) - Jason Day' s stomach was acting up while he was on the driving range Thursday morning, an angry reaction to antibiotics that are supposed to wipe out a lingering, often-misdiagnosed sinus infection.

He was thinking about withdrawing from the Byron Nelson Championship. Then he realized it looked like rain and he'd left his umbrella in the car.

Walking to the parking lot, Day pictured himself getting behind the wheel and heading to his home in Fort Worth. He ended up toughing it out, and "it was probably a good idea," he said with a smile.

Day birdied four of his first six holes on his way to a 4-under 66 for a share of the first-round lead when play was suspended late Thursday.

The threatening skies that sent Day fetching his umbrella never actually drenched the TPC Four Seasons course, but the radar looked so scary there was a delay of 3 hours, 44 minutes.

Joe Durant finished with an eagle and a birdie to match Day at 66. Steve Elkington, Hunter Mahan and Jarrod Lyle were still on the course with scores of 4-under.

Elkington will have two holes left, Mahan three and Lyle seven when play resumes at 7:15 a.m. Friday, pushing back the start of the second round by an hour. Thursday's late starters are the first to go off Friday, which means it will be a long day for them.

Among those working overtime will be 16-year-old Jordan Spieth, a high school junior from Dallas and the reigning U.S. Junior Amateur champion. He's the first high schooler to get a sponsor's exemption into this event since Tiger Woods in 1993, and he showed he belongs by shooting even par through 11 holes.

Spieth woke up nervous and held his emotions in check during the delay by playing table tennis, shopping for souvenirs and putting. After a raucous ovation at his introduction, he ripped his tee shot down the middle, beyond his two playing partners. He parred the first four holes, then dropped in a birdie. He finished with a par putt and walked away saying, "I wanted to keep playing, I didn't care how dark it was."

Dustin Johnson was part of a group tied for second at 3-under, one shot behind. He's No. 9 on the season's money list, the top earner in this field.

Defending champion Rory Sabbatini was among a pack at 68.

Vijay Singh and Rickie Fowler got off to poor starts in their quests to qualify for the U.S. Open. Both need to be near the top of the leaderboard to get into the top 50 in the world rankings by Monday's deadline, but both were stopped at 2-over. Fowler had two holes left, Singh three.

Although the weather made for a long afternoon, it helped Day. He used the down time to recover from the strength-sapping eight-plus holes he'd played.

"I just kind of sat down and rested," Day said. "I just sat down at a table with a bunch of friends and my wife and we sat there and talked, drank a lot of water, tried to keep up with my nutrition at least in there."

After the restart, he sure kept things interesting: two birdies, two bogeys and several scrambling pars - like on No. 1, his first full hole after the break. His tee shot was so poor it landed on the cart path, against a fence.

"I don't think any player has been over there except me today," he said.

Day's season has been a lot like this round, spurts of great shots and bad ones, and ever-present illness.

His physical problems began at the season-opening tournament in Hawaii. He's seen about six doctors trying to figure out what's wrong. The diagnoses he's heard include swine flu, bronchitis and allergies, and he's been given a bunch of different medicines.

Turns out he has a chronic sinus infection. He was given a shot and a batch of heavy antibiotics that should finally clear things up - but only after they threaten to clean him out. That's why he stood on the driving range wondering if 18 holes was a good idea.

"I really didn't think I was going to play this morning," he said.

Now the really weird part: The longer Day's medical woes have dragged, the better he's played. He's had three top-25 finishes this season, all in the last five weeks.

Day suggests it's because he's practiced less and lowered his own expectations.

"I think I'm going out there and trying to play smarter golf," said Day, who is only 22 but grew up being described as Australia's answer to Tiger Woods. "I didn't chip and putt as well as I would like to at the start of the year, and everything is turning around nicely now."

That breakthrough, first PGA Tour win would be even better.