Like Venturi, John Joseph Burke Jr. (Jackie to the public, Jack to his friends) has been a golfer since age of 7. When only 12 he shot a 69, first qualified for U.S. Open at 16, turned pro at 19. Now 33, his youthful appearance earned him Bob Hope's gag, "The pro at Boy's Town," although his real home club is big Concord Hotel in New York's Catskills...Until he won Masters, his first major championship, Burke seemed in danger of developing chronic runner-upitis, not having won a tournament since Inverness in Toledo in 1953. "I was beginning to think I'd never win one," he said. "Second place is nice, but it gets awfully tiring after a while" ...After four war years, Jackie returned to golf under wing of Veteran Jimmy Demaret, who had been his father's assistant when Jackie was youngster. Easygoing Demaret tried to teach serious young Jackie to relax. "Jackie always had the shots," says Jimmy, "but he takes his game too seriously. I tried to teach him to slack off a little bit and loosen up." Jimmy also taught Jackie his love for flashy golfing clothes...Jackie's first big victory was Metropolitan Open in 1949. Then, after long string of seconds, he changed from blade to mallet-type putter in 1952, quickly won four straight on winter circuit and took second in Masters before again assuming also-ran role. However, in three years as Ryder Cup player (1951-53-55) has never been beaten...Still maintains official residence in Houston, with comely wife Ielene and two small sons, but spends most of year on pro circuit. His $6,000 winnings at Augusta put him among top earners this year. Like Venturi, his goal is U.S. Open, where his father tied for second in 1920.