Nathaniel Crosby, youngest son of the late Bing Crosby, drew even with Brian Lindley by winning the 34th and 35th holes of their 36-hole final, then sank a sudden-death 15-foot birdie putt on the 37th yesterday at San Francisco's Olympic Club to capture golf's 81st U.S. Amateur Championship.

Crosby, 19 and a University of Miami sophomore, started poorly in the afternoon portion of the final, going bogey, double bogey, bogey to hand Lindley, 24, an aerospace engineer from Fountain Valley, Calif., a 3-up lead.

Crosby, fingering his father's amateur medallion every time he faced a crucial shot, was 4 down when he finally won a hole -- the 27th -- with a three-foot putt after Lindley missed from 12 feet. But the back nine at Olympic's Lake course had been good to Crosby all week, and it was good to him again when he needed it the most.

On 18, the 36th hole of the day, both made crucial putts to send the match to the extra hole. There, two fine shots left Crosby barely short of the green -- the hole is a par-5, 530-yarder -- he pitched to the edge and ran home the putt to win the first important tournament of his life.

Before this one, the only tournament title Crosby could claim was his home club championship. He won the first one when he was 15 and his father was alive. Bing Crosby died a little later the same year, playing golf in Spain. Nathaniel Crosby recalls setting a goal then to win a major tournament before his 20th birthday, which is next month.

This was the first time since 1950 the tournament was decided in overtime. That year, Sam Urzetta needed three extra holes to beat Frank Stranahan.

Jay Haas stayed comfortably ahead of all rivals and won the pro golf tour's $275,000 B.C. Open at Endicott, N.Y., by the three-shot margin with which he began the final 18 holes.

Haas, demonstrating for the second time this season his ability to nurse a lead, finished with a 270 total, 14 under par. He worked his way to the $49,500 first prize with a closing 69 across the 6,966-yard, par-71 En Joie course. It was much the same script as in July when Haas won the Greater Milwaukee Open by three strokes after leading by five going into the final round.

The script was also familiar for Tom Kite. He finished second for the second straight week and the third time this season. He has 14 other top-10 finishes and the $29,700 B.C. consolation prize boosted him into third place on this year's money list, just ahead of Bruce Lietzke, who took the week off.