SAN FRANCISCO (Interstat) — Landen Roupp pitched five strong innings and the San Francisco Giants broke open a tight game with a four-run eighth inning to beat the Arizona Diamondbacks 6-1 on Thursday night at Oracle Park.

Roupp allowed one run and four hits over five innings, striking out three, to earn his eighth win of the season. The right-hander worked around early traffic and kept Arizona off balance after the Diamondbacks tied the game in the fourth. Roupp walked two and did not allow a home run, a key factor in a game where the Giants bullpen then held Arizona scoreless over the final four innings.

Arizona took a 1-1 tie into the bottom of the fifth, but San Francisco regained the lead on Drew Gilbert’s sacrifice fly. The score remained 2-1 until the Giants erupted in the eighth against the Arizona bullpen. Jung Hoo Lee led off the inning with a walk. After Gilbert lined out, Rafael Devers singled to center field, with Lee advancing to third. Bryce Eldridge then doubled to left, scoring Lee and sending Devers to third. Jonah Cox followed with an RBI single to center, and Turner Hill added a sharp single to right that scored Eldridge. Shay Whitcomb then laid down a sacrifice bunt that brought home Cox, giving San Francisco a 6-1 lead.

The eighth-inning burst made a winner of Roupp, who improved to 8-13. Jose Cabrera took the loss for Arizona, falling to 0-3 after allowing two runs over 4 1/3 innings. Cabrera scattered three hits and struck out four, but the Diamondbacks could not provide him enough support.

San Francisco took the initial lead in the first inning when Gilbert hit his eighth home run of the season, a fly ball to right center off Cabrera. The Giants threatened to add more in the inning after Devers singled and Jonah Cox walked, but Cabrera escaped with a center-field flyout and a groundout.

Arizona answered in the fourth. Gabriel Moreno led off with his 11th home run, a line drive to left field that tied the score at 1. Geraldo Perdomo followed with a single, and after Max Kepler lined out, Tim Tawa walked. Jose Fernandez singled to left, loading the bases with one out. But Ildemaro Vargas flied out to left and Ryan Waldschmidt struck out swinging, leaving the game tied.

The Giants regained the lead in the fifth. Christian Koss was hit by a pitch to open the inning. Nate Furman sacrificed Koss to second, and Gilbert then hit a sacrifice fly to left, scoring Koss and putting San Francisco ahead 2-1. Rafael Devers grounded out to end the inning.

Cabrera kept the game close through the middle innings, but Arizona’s offense was unable to solve Roupp after the fourth. The Diamondbacks managed only two baserunners between the fifth and seventh innings. Lars Nootbaar flied out to center in the fifth, and Arizona went down in order in the sixth against Roupp, who retired the side on a strikeout and two flyouts.

Roupp handed the game to the bullpen after five innings. Taylor Clarke, who followed Cabrera for Arizona, pitched 1 2/3 scoreless innings with one strikeout. Juan Burgos and Jonathan Loáisiga also worked scoreless innings for Arizona, but the damage came in the eighth against the Diamondbacks’ relief corps.

San Francisco’s bullpen was sharp. Trent Harris pitched two scoreless innings, striking out two. Carson Seymour worked a perfect eighth inning, and Ryan Walker closed out the ninth, allowing two hits but no runs while striking out one. The Giants bullpen combined for four scoreless innings, preserving Roupp’s win.

Arizona’s defense had a difficult time generating momentum after its early scoring chance. The Diamondbacks left the bases loaded in the fourth and never again put more than one runner on base in an inning until the ninth, when they had two singles but could not score. Perdomo and Kepler each singled with one out in the ninth, but Tim Tawa struck out and Jose Fernandez grounded into a force out to end the game.

The Giants finished with seven hits, while Arizona had six. San Francisco’s two sacrifice hits were key in manufacturing runs, particularly in the fifth inning when Gilbert’s sacrifice fly proved to be the winning run before the eighth-inning rally. The Giants also executed a sacrifice bunt in the eighth that drove in a run, showing the value of situational hitting.

Arizona fell to 72-64 with the loss, while San Francisco improved to 56-80. The Diamondbacks, who had won two straight against the Chicago Cubs earlier in the week, could not carry that momentum into the series opener. San Francisco snapped a two-game losing streak and picked up a much-needed victory at home.

The game lasted 2 hours, 33 minutes before a crowd of 40,120.

The teams will meet again Friday night in the second game of this four-game series. San Francisco has won four of the last seven meetings between the clubs, though Arizona took two of three in San Francisco in late May. The Diamondbacks and Giants split a two-game set in Arizona in early July, with the home team winning each contest.

Arizona’s upcoming schedule includes two more games in San Francisco before returning home to face the Philadelphia Phillies. The Giants will remain at home for the series against Arizona, then travel to Atlanta and Pittsburgh.

The decisive eighth inning began with a walk to Lee, who had entered as a substitute. Devers’ single was deflected by pitcher Kevin Ginkel, a play that allowed Lee to reach third. Eldridge then delivered a double to left, and the floodgates opened. Cox’s single to center brought home Devers, and Hill’s ground single to right scored Eldridge. Whitcomb’s sacrifice bunt was fielded by pitcher Juan Burgos, but Cox scored easily from third. Drew Cavanaugh flied out to end the inning, but by then the Giants had transformed a one-run game into a five-run advantage.

Arizona’s lone run came on Moreno’s home run, his 11th of the season. The catcher went 1-for-3 with a walk and drove in the team’s only run. Perdomo also had two hits for Arizona, going 2-for-4. Kepler added two singles in the ninth. The Diamondbacks, however, were 0-for-4 with runners in scoring position and left five runners on base.

San Francisco’s Gilbert finished 1-for-3 with a home run, a sacrifice fly and two RBIs. Devers went 2-for-4 with a run scored. Eldridge doubled and drove in a run. Cox had two hits, scored once and drove in a run. Hill had two hits, including the RBI single in the eighth. The Giants’ offense took advantage of Arizona’s pitching mistakes and executed when it mattered.

Roupp’s performance was especially notable given his recent outing against Pittsburgh, where he earned a win with five innings of one-run ball. He followed that with another five-inning effort, keeping Arizona to a single earned run. The Giants’ bullpen, which has struggled at times this season, delivered its best combined effort in recent weeks.

For Arizona, the loss overshadowed an otherwise solid stretch in which the team had won 11 of its previous 15 games. The Diamondbacks remain in contention in the National League wild-card race, but missed opportunities in the fourth inning proved costly.

The Interstat game simulator had projected a final score of Arizona 5, San Francisco 3, with the model favoring the Diamondbacks. The Interstat ELO system gave Arizona a 55.60 percent probability to win. Arizona was installed as a pregame favorite with a spread of minus 1.5. The game’s total score of 7 went over the over-under line of 7.5.