(Adds third inning) DETROIT, Oct 28 - Pre-game: The San Francisco Giants hold a 3-0 lead in the World Series and if they can win on Sunday in chilly Detroit they will become the 21st team to claim the championship with a sweep. The Giants took the first two games in San Francisco, 8-3 and 2-0, before coming to sold-out Comerica Park and winning Game Three 2-0. This is what the rival managers told reporters just before the game. Jim Leyland (Tigers): "I can paint a rosy picture, but the picture is not rosy right now. Our pitching is set up terrific, but you've got to win a game. ...