Two pitchers making important starts at opposite ends of the career spectrum lock horns Saturday when the Washington Nationals duel the San Francisco Giants. For the second time this season, the Nationals are recalling right-hander Reynaldo Lopez from Triple-A Syracuse to start against a playoff contender. The 22-year-old was roughed up for 10 hits and six runs in 4 2/3 innings at home against the Los Angeles Dodgers earlier this month.