But for two errant shots that plopped into water, Couples might have won the Masters and the Byron Nelson.
But for two shots into the water on the same hole, Mattiace might have won the Players Championship.
On Friday they avoided any such disasters and finished 36 holes at Muirfield Village at 9-under-par 135, two strokes ahead of Mark Calcavecchia and Harrison Frazar.
Lurking well within striking distance were a bunch of major championship winners, including Tom Lehman at 138 and Ernie Els, Davis Love III, Justin Leonard and Steve Jones at 139.
"It's such a log jam," Couples said after shooting a 67. "If you go out and shoot 70 or 71 on Sunday you are not going to win."
It will likely take two more rounds in the 60s for someone to walk away with the $396,000 first prize.
Tiger Woods, whose round included a double bogey when he needed two shots to get out of a bunker on No. 14, shot a 74 and was at even-par 144, nine strokes back.
While Couples and Mattiace avoided the water, the Memorial could not avoid the rain that haunts the tournament. When a thunderstorm stopped play for 2 1/2 hours it was the 14th time in 38 rounds over the last nine years that a round in the tournament had been delayed, interrupted or canceled because of rain.
Couples let the Masters slip away with a ball in the water on No. 13 in the last round and lost the Byron Nelson when he splashed a shot on No. 17 on Sunday, both times with errant 6-iron shots.
On Friday, he hit that 6-iron to 15 feet on the 182-yard eighth hole and made the putt for one of his seven birdies as he shot a 67 on a firm and fast Muirfield Village course.
"It's fun to play good again," said the 1992 Masters champion who picked up his 13th career victory at the Bob Hope tournament in January. "It was easier a long time ago," Couples said, referring to 1991 and '92 when he won five times. "But now when I get there I feel pretty good."
Reflecting on his failures to close at victories at the Masters and the Byron Nelson, Couples said: "If I keep playing good on Sunday until the last hour, then I have a problem."
Mattiace, looking for his first win in his fourth full year on tour, had a chance for that victory at the Players Championship in March when he made seven birdies in a 12-hole stretch in the final round and was one stroke behind Leonard with two holes to play.
But two balls in the water on the island-green 17th hole led to a quintuple bogey 8 and sunk his chances.
"The Players Championship gave me a lot of confidence," Mattiace said about that experience. "I made nine birdies on Sunday. That's pretty good. The last couple of months I've grown a lot as a player."
He displayed some of that maturity Friday in a round with five birdies and no bogeys. Carried by strong iron play, the longest birdie putt he made all day was 15 feet and "probably four or five other times" he missed birdies from inside 20 feet.
"It's nice to go around Jack's course with no bogeys," he said about the Muirfield layout designed by tournament organizer Jack Nicklaus. "I think I missed some chances to go even lower."
Frazar is looking for his first victory on tour but the way he has progressed the last three weeks is astounding. After only one top-30 finish in 11 career starts, he finished second at the Byron Nelson two weeks ago and fourth at the Colonial last week.
"It took me a while to get kind of calmed down," he said about adjusting to the tour. "I was in awe of seeing everybody in the clubhouse and I had to learn how to manage the golf course."
He must be a fast learner. His 69 on Friday was his ninth round of his last 11 that was below 70.
Among those missing the cut for the weekend were Phil Mickelson, Scott Hoch, Fuzzy Zoeller and Nicklaus.
Woods, whose iron play was weak and putting even weaker, has proven time and again that he is capable of coming from far back. Last year at Pebble Beach he trailed by 10 strokes and finished with a 63 and 64 to miss a playoff by one stroke.
In Thailand this year, he trailed Els by 11 strokes with 36 holes to play and caught him, winning in a playoff.
"I've got to play two good rounds and see what happens," Woods said. "But more importantly I've just to go out there and play my own game and try to get myself back in it, and if not _ oh well."