* U.S. win three matches out of six in opening fourballs
* Internationals mount fightback after weather delay (Adds quotes, further detail)
By Mark Lamport-Stokes
DUBLIN, Ohio, Oct 3 (Reuters) - The United States needed a par on the final hole to retain the overall lead over the Internationals on the first day of the Presidents Cup after almost throwing away a commanding advantage following a lengthy weather delay.
Steve Stricker calmly got up and down from a plugged lie in a greenside bunker to par the 18th, sinking a three-footer to secure the decisive point that allowed the Americans to finish the opening fourballs leading by 3-1/2 points to 2-1/2.
At one point, the Americans led in all six encounters at rain-softened Muirfield Village Golf Club where birdies were plentiful but South Africans Louis Oosthuizen and Charl Schwartzel inspired a stirring fightback by the Internationals.
Oosthuizen and Schwartzel, who briefly donned garish wigs on the first tee, came from two down after seven holes to beat British Open champion Phil Mickelson and Keegan Bradley 2&1 in a contest of high quality involving four former major winners.
Bradley put the Americans two up by sinking a six-foot eagle putt at the par-five seventh but the South Africans won the next two holes with birdies, Oosthuizen draining a 16-footer at the eighth and Schwartzel tapping in a two-footer at the ninth.
Oosthuizen then put the Internationals one up by knocking in a three-foot birdie putt at the par-five 11th, and his good friend Schwartzel sealed victory with a birdie at the 17th.
"We knew it was going to be difficult, Keegan and Phil are a great team," said 2010 British Open winner Oosthuizen.
"I think the break did us all really well," he added, referring to a thunderstorm delay of just under an hour-and-a-half which effectively stalled the early U.S. momentum. "We came back out and felt refreshed.
"We just played well. Whenever Charl was in trouble; I played really well. And whenever I was in trouble, Charl played well."
Tiger Woods and Matt Kuchar earned the first point of the day for the U.S., hammering Argentina's Angel Cabrera and Australian Marc Leishman 5&4 in a match they led from the opening hole.
"We ham-and-egged it pretty good," said Woods. "Kuch made a bunch of putts on the front nine, I got it rolling there for a little bit and on the back nine. It was him or me on each hole."
Zach Johnson and PGA Championship winner Jason Dufner never trailed before beating South Africans Branden Grace and Richard Sterne 5&3 while Stricker and Jordan Spieth ended a birdie fest against South African Ernie Els and Zimbabwe's Brendon de Jonge with a hard-fought 1-up win.
However, the Internationals did well to salvage 1-1/2 more points from two of the earlier matches out.
Australian Jason Day sank a 22-foot birdie putt at the last to seal a 1-up win in tandem with Canada's Graham DeLaet over Hunter Mahan and Brandt Snedeker, after they had been three down after six holes.
Masters champion Adam Scott of Australia and Japan's Hideki Matsuyama, who never led and trailed by two with four holes to play, fought back to square their match against Bill Haas and Webb Simpson.
The 21-year-old Matsuyama almost sank his approach at the last, his tap-in for birdie earning the Internationals a valuable half-point.
"What we showed today is that there's plenty of heart on this team," said Scott, who has competed in five previous Presidents Cups but has yet to taste an International victory.
"We were in ordinary shape for a while and now, 3-1/2 to 2-1/2 isn't a big deal."
Prior to their late fightback, the Internationals were clearly feeling the pressure in the matchplay format they prefer, as they have traditionally struggled in the foursomes.
Their captain Nick Price felt he had gained a valuable concession with fourballs featuring in the opening Cup session for the first time since the 1996 edition of the biennial team competition, and had been hoping for a fast start.
But it was the Americans who came charging out of the gate after former U.S. President George W. Bush had greeted both teams before they teed off at the par-four first in front of packed grandstands.
U.S. captain Fred Couples, who was given a cake by the International team for his 54th birthday, watched in delight as his players seized early control before play was suspended due to the threat of lightning.
"Our guys were rocking and rolling," said Couples. "The rain delay obviously helped them. They played their hearts out."
The U.S. have dominated the Presidents Cup by winning seven times in nine editions, most recently with a 19-15 victory at Royal Melbourne Golf Club in Australia two years ago.
The only success for the Internationals came in 1998 when the event was first staged in Melbourne. In 2003, the two teams battled to a 17-17 draw in South Africa. (Editing by Julian Linden/Greg Stutchbury)