Following Wednesday's scheduled off-day, the Giants will visit the D-backs for a key four-game series beginning Thursday at Chase Field. It'll be a challenge for San Francisco, which is separated from the first-place Dodgers in the National League West by both Arizona and Colorado. Left-hander Madison Bumgarner, who will start the series opener for the Giants, is winless in his last four outings against the Rockies despite a 2.67 ERA in that span. First pitch is scheduled for 6:40 p.m. PT. No starter has been announced for the D-backs.