SAN FRANCISCO (Interstat) — Merrill Kelly pitched six strong innings and the Arizona Diamondbacks broke open a tight game with a three-run fifth inning to defeat the San Francisco Giants 6-2 on Monday night at Oracle Park.

Kelly allowed two runs on five hits over six innings, striking out three and walking two, to improve to 5-3 on the season. He allowed the only Giants runs in the fourth inning but settled down to retire the final seven batters he faced before giving way to the bullpen.

Landen Roupp took the loss for San Francisco, falling to 5-5. Roupp allowed four runs on nine hits over 4 1/3 innings, striking out six. He walked one.

The Diamondbacks improved to 29-24 with their fourth consecutive victory. The Giants dropped to 22-32.

Arizona drew first blood in the third inning. Gabriel Moreno led off with a solo home run to center field, his third of the season. The Diamondbacks then loaded the bases on singles from Tommy Troy, Ketel Marte and Corbin Carroll, but Roupp struck out Geraldo Perdomo and got Nolan Arenado to fly out to escape further damage.

The Giants answered in the bottom of the fourth. Willy Adames walked to lead off and moved to third on a double by Luis Arraez. After Casey Schmitt struck out, Rafael Devers doubled sharply to right field, scoring Adames and Arraez to give San Francisco a 2-1 lead. Kelly then retired Matt Chapman and Daniel Susac to end the inning.

Arizona regained the lead in the fifth. Tommy Troy reached second on a throwing error by Adames leading off. Marte followed with an RBI double to left field, scoring Troy to tie the game. After Carroll lined out, Perdomo singled up the middle to bring home Marte and put the Diamondbacks ahead 3-2. Adrian Del Castillo added an RBI single to center field, scoring Perdomo to make it 4-2.

The Diamondbacks padded their lead in the sixth. Moreno walked and Jose Fernandez doubled to left field, putting runners at second and third. After Troy flied out, Marte singled to center field, driving in both Moreno and Fernandez for a 6-2 advantage.

Marte finished 3-for-5 with three RBIs and two runs scored. Carroll had two hits. Perdomo added two hits and an RBI. The Diamondbacks collected 11 hits total.

For the Giants, Devers drove in both runs with his double. Arraez had two hits, including a double. Drew Gilbert singled and doubled. San Francisco managed only five hits.

Kelly allowed the two runs in the fourth but then retired six straight before leaving after the sixth. Jonathan Loáisiga pitched a scoreless seventh inning, allowing one hit and striking out one. Justin Martinez worked a scoreless eighth, allowing a double to Gilbert but stranding him at third. Kevin Ginkel closed out the ninth, allowing a hit by pitch to Devers but inducing a double play and striking out Susac to end the game.

San Francisco’s bullpen kept the game within reach after Roupp departed. JT Brubaker threw three scoreless innings, allowing one hit and striking out one. Sam Hentges tossed two-thirds of an inning, allowing one hit and striking out one. Joel Peguero gave up two runs on two hits in one-third of an inning.

The Giants had opportunities early. In the first inning, Adames singled with one out but was erased on a double play groundout by Schmitt. In the third, San Francisco went down in order. In the fourth, the Giants took the lead with two runs, but Kelly quickly settled.

Arizona put the game away with the three-run fifth, and Kelly made the lead stand.

The Diamondbacks have now won four in a row and eight of their last 10 games. They improved to 6-2 against the Giants this season, having swept a three-game series in Arizona earlier this month. The Giants have lost four of their last five.

The attendance was 38,380. The game lasted 2 hours, 36 minutes.

The two teams meet again Tuesday night in the second game of this three-game series. Arizona will send left-hander Eduardo Rodriguez to the mound, while San Francisco will counter with right-hander Jordan Hicks.

Looking ahead, the Diamondbacks travel to Seattle for a three-game weekend series starting Friday. The Giants head to Colorado for three games beginning Friday.

In pregame projections, Interstat’s game simulator had projected a final score of Arizona Diamondbacks 6, San Francisco Giants 4. Interstat’s ELO system gave Arizona a 51.70 percent probability to win. San Francisco was installed as a pregame favorite with a spread of minus 1.5. The total score of 8 went under the over-under line of 7.5.