Lee Elder of Washington, D.C., who led from start to finish, shot a final-round par 72 for a 72-hole total of 281 and won the $320,000 Grand Slam golf tournament by seven strokes yesterday in Yokohama, Japan. He won $48,890 and a Japanese car.

It was the first victory on the senior professional tour for Elder, who became eligible in July when he reached his 50th birthday. It also was his first tour victory since the 1978 Westchester Classic . . .

Virginian Curtis Strange, never really threatened, managed a front-running, one-under-par 71 and took the LaJet Classic at Fairway Oaks in Abilene, Tex., by two shots. With $63,000 from the total purse of $350,000, Strange's season earnings reached a career-best $276,773.

Strange, six ahead when play started, acquired the fifth title of his eight-year PGA Tour career with a 273 total, 15 under par. Mark O'Meara came on with a 66 and finished second a fifth time this year.

Strange, leading by three, drove into water on the 17th but salvaged bogey. He went to the 18th needing only a bogey 6 to win; he made par . . .

In Virginia Water, England, Seve Ballesteros curled in a nine-foot putt on the 35th hole to defeat Bernhard Langer, 2 and 1, and win the $183,000 Suntory World Match Play.

Ballesteros was 3 up after 18 holes after shooting seven birdies in the morning round. But he had to rally over the final holes to win the title for the third time in four years and earn the $56,250 first prize.

In the 18-hole playoff for third place, Greg Norman and Ben Crenshaw played to a tie . . .