Castro put the perfect finishing touch on this most wild day at Congressional when he hit his approach into the water left of the 18th green, and then chipped in for par from 80 feet to salvage an even-par 71 and keep a share of the lead.
Haas made nine birdies and had to settle for a 68, courtesy of two wedge shots that cost him four shots, including his triple bogey on the beastly 11th hole. Romero had a three-shot lead at one point, and then it was gone. He went from the water to a bunker on the 11th for double bogey and followed that with a bogey on the next hole. He made six pars the rest of the way for a 70.
Driscoll, meanwhile, motored along without too much excitement. He had a 68, the only player in the field to break 70 all three rounds. Coming off a bogey on the 15th, Driscoll though he might be headed for another with a poor tee shot. But he knocked a 4-iron out of the rough, barely got onto the green and rolled in a 25-foot birdie.
They were at 7-under 206, and more fun awaits Sunday.
"I think over four days here, every player is going to hit kind of a rough patch," Castro said.
Ten players were separated by four shots going into the final round, a group that includes 19-year-old Jordan Spieth. He had a two-shot lead after opening with two straight birdies, and then went through a stretch of missing five putts inside 8 feet on a four-hole stretch. One of them was a three-putt from 5 feet for double bogey on No. 8. Spieth had a 74, though he's still in the game, just three shots behind.
"A wild day," Castro said.
Jason Kokrak had a 70 and was one shot out of the lead, while Charlie Wi had a 29 on the front nine and shot 65 to finish two shots behind, along with Tom Gillis (66). Spieth was in the group at 209 with Brandt Snedeker, who had a 69.
If Saturday was any indication, expect anything in the final round, especially since seven of those 10 players have never won on the PGA Tour.
"The back nine, I didn't really know where I was going," Haas said. "Luckily after that triple, I was able to hit three decent iron shots and then make the putt. Certainly, it could have been a 6-, 7-, 8-under day. But it also could have been a 4-, 5-, 6-over day if I hadn't putted well. I don't really know what to make of how I'm playing. Just got to hopefully do more good than bad tomorrow."
Spieth had a two-shot lead when he walked off the third green. Five holes later, he was four shots behind.
Haas was five shots behind after his triple bogey. Four holes later, he had the lead to himself.
Romero was the only player to reach 10 under at any point, with four birdies on the front nine, including a sand wedge out of ankle-deep rough left of the eighth fairway to about 5 feet. He was sailing along until he set up for a fade on the 11th hole and came off the shot, sending it into the hazard.
Castro's problems were early, and not entirely up to him. After a bogey on the par-3 second hole when he was on the down slope of a bunker to a short pin, he hit a tee shot right of the third fairway. Just his luck, the ball landed in the soft sand at the edge of the grass and disappeared. The ball was buried under an inch of sand that Castro had to scrape away just to make sure the ball was his.
He took a penalty shot to drop it in the middle of the bunker, couldn't reach the green and made double bogey. He hit great putts just to save par on the next two holes which settled him down and he made only one bogey the rest of the way.
It looked early on as though the more times Spieth put himself in contention, the more comfortable he would be. That only lasted a short time.
He opened with a 10-foot birdie putt and followed that with a tee shot that used the backstop perfectly on the par-3 second, the ball rolling back down the hill to 2 feet for a tap-in birdie. After a good par on the third hole, he had a two-shot lead.
Five holes later, he was four shots behind.
That's how quickly the scores changed on a balmy Saturday at Congressional not just for Spieth, but for everyone.
Spieth's troubles began when he missed the green long and right on the fifth hole, leaving him a downhill chip to an elevated green. The best he could do was 15 feet and he missed his par putt, ending his streak of 33 straight holes without a bogey.
He missed an 8-foot birdie putt on the par-5 sixth. After hitting 3-wood into thick rough left of the fairway at No. 8 and hacking out short of the green, Spieth had a chance to save par until he missed from 5 feet and then missed from 3 feet and made double bogey. And on the ninth, his wedge spun off the front of the green and rolled down the hill, leading to another bogey. If that wasn't enough, he missed a 7-foot birdie putt on the 10th.
Romero pushed his tee shot into the hazard on No. 11 and made double bogey, and a bogey on the 12th cost him his three-shot lead. Spieth was still only two shots behind, though his sagging shoulders suggested the deficit was much larger.
Haas was making a steady climb toward the leaders until he hit into the rough on the 11th, pitched out to the fairway and then hit wedge into the water. On the par-5 16th, Haas hit another poor wedge that came up short and led to bogey.
He could have done without the excitement. Haas had to play nine holes in the morning to complete his rain-delayed second round.
"Looking forward to tomorrow to hopefully make nine birdies or half that," he said. "I'll take four or five birdies tomorrow and eliminate some mistakes, and maybe win this thing."
Copyright 2013 The Associated Press.