Delgado (2-3) scattered three hits, overcoming four walks and striking out two in an 89-pitch effort.
Arizona led 1-0 for most of the game until Cody Ross delivered a two-run single in eighth, providing some much-needed insurance as the D-backs avoided a three-game sweep and retained a half-game lead over the Los Angeles Dodgers atop the National League West.
Paul Goldschmidt went 3-for-4 for Arizona with two runs scored, raising his average to .309.
The loss went to Giants' Madison Bumgarner (10-6), who allowed just one run on five hits in seven innings.
Notable deaths of 2014 [PHOTOS]
UPI Sports Results for September 19, 2014