Scotsman Sam Torrance, whose final putt at the Belfry ended 28 years of U.S. Ryder Cup domination last month, yesterday contributed to the top-seeded United States gaining the final of golf's richest tournament, the $1.2 million Dunhill Cup in St. Andrews, Scotland.

With fourth-seeded Scotland trailing, 1-0, but leading the third match, Torrance led Curtis Strange by one stroke. Torrance bogeyed the 17th and 18th, missing an 18-inch putt in front of a large partisan gallery.

Strange's par 72 gave him a one-stroke victory.

In other matches, American Mark O'Meara shot 69 to beat British Open champion Sandy Lyle by three strokes and Raymond Floyd became the first American to lose a match when his 72 was bettered by Gordon Brand Jr. by one stroke.

Australia beat Wales, 2-1 . . .

Defending champion Lee Elder of Washington, D.C., shot a five-under-par 67 for seven-under 137 and the second-round lead of a PGA Seniors tournament in Melbourne, Fla. First-round leader Jim Ferree shared second with Don January and Peter Thomson at 138. Elder has an eagle 3 on the 505-yard, par-5 first hole, four birdies and one bogey . . .

Ken Brown shot six birdies on the front side in a 64, tying Danny Edwards and John Cook for the third-round lead at 11-under-par 202 in the Pensacola (Fla.) Open. At 203 were Gil Morgan, Mark McCumber, Calvin Peete and Steve Bowman.