SAN DIEGO >> For the final four weeks of the regular season, the Dodgers' challenge will look a lot like it did this weekend at Petco Park.They have only one series remaining (Sept. 18-20 against the Pittsburgh Pirates) against a team with a higher winning percentage than their own. The San Francisco Giants, 7 1/2 games out of first place in the NL West with 25 to play, are becoming less of a threat each day.