Gorkys Hernandez hit Jake Diekman's first pitch for a walk-off single in the ninth inning Tuesday night, giving the host San Francisco Giants a second straight win over the first-place Arizona Diamondbacks, 1-0.

The game began as a classic pitchers' duel between Diamondbacks right-hander Clay Buchholz and Giants lefty Madison Bumgarner. The contest ended when San Francisco strung together a walk to Steven Duggar and singles by Nick Hundley and Hernandez with one out in the ninth to complete their ninth walk-off win of the season.

The fourth-place Giants (67-67) got back to the .500 mark for the first time since 61-61 and moved within six games of first place in the National League West. The Diamondbacks (72-60) dropped into a tie for the division lead with the Colorado Rockies, who beat the Los Angeles Angels 3-2.

Arizona and San Francisco wrap up their three-game series Wednesday.

Hernandez's hit came after the Giants had sent Alen Hanson to the plate to bat for winning pitcher Will Smith (2-2) with runners at first and second in the ninth.

The Diamondbacks countered by replacing right-hander Brad Ziegler (1-6) with the left-handed Diekman, prompting the Giants to switch to Hernandez, a right-handed hitter.

One pitch later, the Diamondbacks had been dealt a fourth loss in five games.

Smith pitched a 1-2-3 top of the ninth to get the win.

Neither starting pitcher got a decision.

Bumgarner pitched out of a bases-loaded, one-out jam in the sixth and completed seven shutout innings. He allowed four hits and four walks while striking out five.

A single by Paul Goldschmidt, a walk to Eduardo Escobar, and one out later, a single by Nick Ahmed loaded the bases for the Diamondbacks in the sixth.

But Bumgarner got Ketel Marte to hit into a fielder's choice at the plate, and then retired Jeff Mathis on a fly to center to end the threat.

Buchholz matched Bumgarner basically pitch-for-pitch, also throwing seven shutout innings. He gave up five hits, walked two and struck out three.

The Giants' best chance to score against Buchholz came in the third when Andrew McCutchen walked with two outs and Joe Panik singled to right-center, sending McCutchen to third.

However, Panik tried to take second on the hit and was thrown out, ending the inning.

Hundley had two hits for the Giants, who did not record an extra-base hit among their seven hits in the game.

Marte collected a double and a single, while Ahmed had two hits for the Diamondbacks, who fell to 0-2 at the start of a seven-game trip. Arizona had six hits.

--Field Level Media