Randal Grichuk hit two home runs, Ryne Nelson pitched effectively into the seventh inning and the Arizona Diamondbacks opened a key three-game road series by holding on for an 8-7 victory over the San Francisco Giants on Tuesday night.

With just a second win in their last six games, the Diamondbacks (78-61) retained the No. 2 wild-card position in the National League while also putting 10 games between them and the sinking Giants (68-71).

Grichuk got the Diamondbacks rolling with a two-run homer in a three-run first inning, then added a solo shot leading off the fifth as Arizona ran up a 7-1 lead.

The two-homer game was the 12th of Grichuk’s career. The homers were just his seventh and eighth this season.

Kevin Newman chipped in with a two-run single for the Diamondbacks, who knocked out Giants starter Kyle Harrison (7-7) after just 2 2/3 innings. The left-hander was charged with six runs on seven hits, with one walk and three strikeouts.

Nelson (10-6) left with a 7-2 lead with two outs in the seventh, having limited the Giants to just four hits. He walked two and struck out nine.

The Giants rallied against the Arizona bullpen in the eighth after Mike Yastrzemski led off the inning with his 13th homer.

A Jerar Encarnacion single, Patrick Bailey bunt and Marco Luciano single also produced single runs, getting the Giants within 7-6 with runners at first and third with two outs. But Justin Martinez struck out Luis Matos to escape the jam.

The visitors were able to tack on a run in the ninth when Corbin Carroll singled, stole second and came home on a Christian Walker single.

The extra run eased the burden on Martinez in the last of the ninth. He served up a one-out double to Heliot Ramos that made it a one-run game again, but then picked up his eighth save by retiring two of the final three men he faced, including striking out Encarnacion with two aboard to end it.

Grichuk finished 3-for-5 with three runs and three RBIs for the Diamondbacks, whose 11 hits matched the Giants’ total. Carroll collected a double, single and two runs, while Newman and Geraldo Perdomo added two hits apiece.

Yastrzemski had two hits and scored three times, while Ramos and Bailey had a pair of hits apiece for the Giants, who fell to 1-3 on their make-or-break, six-game homestand.