Sheehan completed only No. 1 at the Redstone Golf Club, and his co-leaders had just teed off in the twilight when tournament officials called a halt because of darkness.
The round didn't begin until late afternoon after a rain delay of more than seven hours. When the rain stopped, 30 golfers took to the soggy course to finish a second round also cut short by bad weather and darkness.
Play was scheduled to resume at 8:30 a.m. ET Sunday with the fourth round to follow as conditions allow. Officials hoped the final round could begin before noon, but the weather forecast called for more rain overnight.
PGA Tour officials said the event could be extended to Monday.
'We have to complete 72 holes,' tournament director Mark Russell said.
After play stopped Saturday evening, another heavy shower hit the course.
'Playing 36 holes, if that's what we have to do, you just go to the next round and that's a little bit of a pressure-free situation,' said Lowery, who closed out the second round Friday with three birdies to grab a share of the lead after two rounds. 'You're in the middle of a round. You don't sleep on it. You just go ahead and play.
'I just think it's whoever gets the momentum tomorrow.'
Lowery, who has made the cut now in seven of 10 events this year, has only one top-25 finish, a tie for 15th last month at Bay Hill. The 43-year-old player has won twice on the tour but not since 2000.
Johnson, the BellSouth Classic winner earlier this month, shot a 4-under 68 on Friday to match Lowery (69) and Stricker (70) at 139.
Jose Coceres had a pair of birdies through four holes, while Geoff Ogilvy, Mark Calcavecchia and Scott Hoch birdied in the brief play Saturday to get to 4-under, level with Vijay Singh, Paul Azinger and John Riegger.
'Instead of a 100-yard dash, you're going to have a 220,' Hoch said. 'If you're in the lead ... the way it is now, you shouldn't even be worried about it.'
Hal Sutton, a winner of this event three years ago, and Justin Leonard were in group of nine players another shot back.
The tournament is the fifth this year on the PGA Tour to endure a suspension of play.
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