Spieth and every other early finisher within three shots of the lead had a birdie 2 on what was supposed to be the par-four 14th Friday. An overnight rain storm turned one of the signature holes at the saturated TPC Four Seasons into a pitch-and-putt par-three hole at 105 yards.
Steven Bowditch, Jon Curran and Texan Jimmy Walker are tied for the lead a nine under. Gary Woodland had a hole-in-one at the 14th.
“I was able to fire at more pins, not really worry about anybody else,” said Spieth, who shot 64 — five under because par became 69 to put him at six under for the tournament. “Really actually helped because I didn't know what score I was at when it's a par four, four par, par three, don't really know what it's at.”
Walker, who won the Texas Open not far from home in San Antonio in March, finished with a par at 18 just before play was halted by darkness. He had a 66 to reach nine under.
There were 33 players on the course after the start was delayed three hours.
“I got little kids,” said Walker, a five-time winner who is second to Spieth in FedEx Cup points. “We didn't want to have to get up earlier again and go do that.”
Bowditch, the first-round leader, shot 68 with seven birdies and six bogeys. Curran matched the day's low round at 63. All three were at 130 with the two-round par total at 139 instead of 140. Cameron Percy was a shot back after an eagle at the par-five seventh for a 64.
Defending champion Brendon Todd shot 68 and was 1 over for the tournament with the projected cut at one-under 138.
Early exits are becoming a habit for Rory McIlroy, especially in his home country, where the 26-year-old Northern Ireland native failed to make the Irish Open cut for the third straight year, shooting an even-par 71 that failed to make up for an 80 in the opening round.
It is the second straight week the world's top-ranked golfer failed to make the weekend, having exited early at the PGA Championship at Wentworth.
This one, he said, hurt more because it's personal. “Obviously I'm playing at home in front of a lot of friends and family. To not play the way I wanted is very disappointing. But I'm sort of getting used to it,” said a downcast McIlroy, whose Rory Foundation charity hosted the Irish Open for the first time.
England's Tyrrell Hatton showed the field at Royal County Down in Newcastle that the seaside links course, bedeviled with unseasonably frigid gales and pelting showers, could be tamed.
The 23-year-old Hatton, ranked 142nd in the world, set a new course record of 66 to join a five-way tie for the lead at three-under 139. His score tied a mark from 1939, but club and European Tour officials said it was considered a new record because the course has greatly changed over the past 76 years.
Only 15 of the 156-player field managed to beat par Friday as the changing weather drove the cutoff score to five over.
Ireland's Shane Lowry summed up the sense of frustration when he smashed his putter against his bag and broke it after missing a short putt for par on his third hole. Lowry actually played better when forced to putt with his wedge, managing three birdies and making the cut with a 74.
Morgan Pressel closed with a birdie and an eagle for a five-under 66 and a one-stroke lead Friday after the first round of the ShopRite LPGA Classic in Galloway Township, N.J.
The 27-year-old Pressel, seeking her first LPGA Tour win since 2008, held the advantage over Anna Nordqvist of Sweden, Alena Sharp of Canada, rookie Min Lee of Taiwan and American Ryann O'Toole on the Bay Course at Stockton Seaview, where the weather was near-perfect.
Brooke Henderson, the 17-year-old Canadian playing on a sponsor exemption, was among nine players at 68. The group included Women's British Open champion Mo Martin, Catriona Matthew and Gerina Piller.
Pressel, ninth on the money list with more than $443,000, hit a wedge close to set up a birdie on the par-four eighth and hit a 5-hybrid from 225 yards to within three feet for the closing eagle on the par-five ninth.