* Mickelson and Bradley win first point for U.S.
* Opening foursomes spills over into Saturday
* Weather delay for second day at Presidents Cup (Adds detail, further quotes)
By Mark Lamport-Stokes
DUBLIN, Ohio, Oct 4 (Reuters) - With Phil Mickelson and Keegan Bradley setting the tone, the United States remained one point in front of the Internationals when Friday's weather-hit foursomes were suspended for the day at the Presidents Cup.
Mickelson and Bradley completed a 4&3 win over Australian Jason Day and Canada's Graham DeLaet in the top match, before South African Ernie Els and Zimbabwean Brendon de Jonge triumphed by the same margin against Bill Haas and Hunter Mahan.
That put the United States ahead by 4-1/2 points to 3-1/2 overall in their bid to win the trophy for an eighth time in the biennial team competition. They led in two of the four remaining matches and trailed in two.
Only two encounters were able to finish at Muirfield Village Golf Club on Friday following a weather delay of just over two-and-a-half hours due to a thunderstorm.
Play will resume at 7.35 am local (1135 GMT) on Saturday in what could be a marathon day, with five fourball matches and five more foursomes also on the schedule, though further thunderstorms have been forecast.
In a worst case scenario, the 10th Presidents Cup could spill over into a Monday finish.
"Monday is a consideration ... if we don't finish by sunset on Monday, then the team with the most points at that point would be declared the winner," tournament director Steve Carman told reporters.
"It's going to be a long weekend, that's for sure," said Masters champion Adam Scott who, in partnership with Japan's Hideki Matsuyama, was four up on Zach Johnson and Jason Dufner after 11 holes. "Time to go rest up."
Steve Stricker and 20-year-old rookie Jordan Spieth were three up on South Africans Branden Grace and Richard Sterne after 14 holes while Tiger Woods and Matt Kuchar were three up on South Africans Louis Oosthuizen and Charl Schwartzel after 12 in the day's marquee match.
"We are playing well, both of us are playing well," said Woods. "I hit a couple of loose iron shots this afternoon, but made a couple good putts and we just kind of put the heat on these guys.
"Seven under (par) through 11 (holes), that's not bad in alternate shot. It's just one of those days where both teams are really playing well, but we still got our work cut out for us tomorrow."
The Internationals, who have lost the last seven sessions of foursomes played at the Presidents Cup, had welcome blue numbers on the leaderboard in the fourth and last matches out.
Argentina's Angel Cabrera and Australian Marc Leishman were one up on Webb Simpson and Brandt Snedeker after 13 holes while Scott and Matsuyama were firmly in control against Johnson and Dufner, having gone three up after just six holes.
Mickelson and Bradley had earlier staged a stirring comeback for the United States in the top match before torrential rain swept across the course and, as thunder rumbled overhead, the siren sounded at 3:09 p.m. to halt the action.
The two Americans did well to go just one down after being outplayed by Day and DeLaet over the first four holes, then won the fifth, sixth, seventh and eighth to go three up.
Left-hander Mickelson sparked the fightback by sinking a 15-foot eagle putt from the fringe at the par-five fifth before hitting a stunning approach to inside two feet at the par-four sixth in the alternate-shot format.
Though the American duo stumbled late in the round, losing the 13th and 14th with successive bogeys after going six up with six to play, they sealed victory when Bradley sank a three-foot birdie putt at the par-five 15th.
"The par putt Keegan made on four was just a critical one," said Mickelson, after he and his partner had rebounded from their loss to Oosthuizen and Schwartzel in Thursday's opening fourballs.
"We were going to go two down and he makes a 15, 18-footer for par and gave us this momentum boost. We were down but, boy, on five we just turned it on and played some of our best golf."
The American duo recorded six birdies and an eagle in their 15 holes to secure victory.
Els and de Jonge, eight under par after 15 holes in the alternate-shot format, were also delighted to celebrate their first win of the week after being defeated by Stricker and Spieth the previous day.
"We both played great today," said Cup rookie de Jonge, who made eight birdies on his own ball in Thursday's loss. "We kept the pressure on them from the start which was obviously the key in this format. Nice to get that win under our belt."
Els said: "Brendon played awesome. He played great yesterday. Actually he even played better today, so a really nice day. We hit some putts early, got some holes early on and kept the pressure on."
The United States, who have won the last four Presidents Cups, led by 3-1/2 points to 2-1/2 after Thursday's fourball matches when play was also interrupted by a thunderstorm. (Editing by Gene Cherry/Peter Rutherford)