CASTLE ROCK, Colo. - Zach Johnson kept his head up and waited for things to get better, as he knew they would.

Even though he missed four makable birdie putts and bogeyed one of the five holes he had to play at dawn Saturday to complete his rain-delayed second round, Johnson had an inkling this was going to be his day at the International.

Sure enough, he birdied five holes and eagled another for a 15-point third round and the 54-hole lead at golf’s most novel event, one which features two cuts and uses the modified Stableford scoring system.

“I had a makable birdie put on 5, 6, 7 and 8 and then I actually made a good bogey on 9,” Johnson said. “It was unfortunate, I hit one in the water on 9, but at the same time, I made a pretty good save.”

And the optimistic 30-year-old player went to the clubhouse at Castle Pines feeling good about his game instead of lamenting his lost opportunities.

That positive attitude paid off for Johnson, whose 27 points heading into Sunday are one more than Steve Flesch and two more than Stewart Cink and Ian Leggatt. Tom Lehman is three points behind in fifth place.

But this isn’t like stroke play. Big changes are the norm at the International, the only stop on the PGA Tour that uses the special scoring system that awards five points for eagles, two for birdies, nothing for pars and deducts one for bogeys and three for double-bogeys or worse.

So, mathematically, just about all of the 33 remaining golfers have a shot at the $990,000 winner’s check.

“The point system kind of keeps it real going into the last day,” said Flesch, who has yet to eagle and is kicking himself for not playing more aggressively before Round 3 on the lush 7,619-yard layout.

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Phil Mickelson failed to make the cut Saturday morning and will some unexpected extra time to focus on the PGA Championship at Medinah next week instead of chasing his third title at the International.

Mickelson’s putter failed him for 36 holes in the lush foothills of the Rocky Mountains, leaving him with just five points. Still, he wasn’t worried heading into the last major of the season.

“I think it’s more just the putting,” Mickelson said. “I’ve just really struggled on the greens here. Otherwise, I’ve been pretty pleased with the way I’m hitting it.”

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Johnson, 30, who won the 2004 BellSouth Classic in his first year on the tour, was among half the field of 140 golfers who had to return to Castle Pines at dawn to complete the second round. Play was delayed more than 3½ hours by a thunderstorm Friday afternoon that dumped more than a half inch of rain on the majestic mountain course.

Finishing on the front nine, Johnson’s putter failed him for four holes before he teed off into the water, providing no hint to anybody but himself of what was to come.