The old guard of the National League West will meet the potential successor as September will be ushered in this weekend with a four-game showdown at Dodger Stadium. The Dodgers have won five consecutive NL West titles, but the Diamondbacks are poised to make a change at the top, and a weekend series in Los Angeles, starting Thursday, figures to set the tone for the drama ahead. The Diamondbacks have held the top spot in the National League West in all but two days in August.