Nelson (9-6) gave up two runs and five hits while striking out seven and walking one to help Arizona win its fourth straight — all on the road. During one stretch, the right-hander retired eight straight and escaped a bases-loaded jam in the third inning.

“(Arizona catcher Adrian Del Castillo) was hanging with me back there. Maybe they were thinking something else,” said Nelson, who was informed by the media after the game that manager Torey Lovullo said pregame he would remain in Arizona’s starting rotation.

“Can’t let that change anything. Have to stay with my process and go out there and give this team the best chance to win,” Nelson said.

Bryan Bello (11-6) took the loss for Boston, which entered the game trailing by 3 1/2 games for the final AL wild-card playoff berth. The right-hander was charged with five runs and seven hits. He walked three and struck out two.

“The walks put him in a bad spot. When you do that at this level, you’re going to pay the price,” Boston manager Alex Cora said.

Rob Refsnyder, a late addition to Boston’s starting lineup, hit a solo home run. Wilyer Abreu drove in the other run with a double.

“That was a tough one,” Refsnyder said after the Sox fell to 29-33 at Fenway Park this season. “We’ve been playing well on the road, but we’ve got to step it up at home especially with the fans still coming out and cheering us on. We owe the fans a lot better.”

Bello settled down after a rocky opening inning that saw Arizona’s first four hitters reach and score twice. Bell drew a bases-loaded walk while Lourdes Gurriel lifted a sacrifice fly that staked Nelson to a 2-0 lead before he threw a pitch.

Boston got one run back in the bottom of the first as Jarren Duran led off the inning with a double and scored Abreu’s double. It remained a one-run game in Arizona’s favour heading into the sixth when the Diamondbacks chased Bello from the game. The pitcher didn’t help his cause with a throwing error on an infield base hit by Adrian Del Castillo.

The hit-and-error sequence was followed by three straight run-producing hits that helped Arizona pull away. Suárez singled in one run, then Luis Guillorme doubled in another run. Perdomo stretched the lead to 5-1 with an RBI single.

Refsnyder’s eighth homer of the season landed over the right-field bullpens but that was as close as Boston would come over the final three innings. The Red Sox were on their second relief pitcher of the night as Suárez jumped on a 1-0 pitch from Josh Winckowski and sent it into the Green Monster seats for his fifth career grand slam.

Arizona added two more runs in the ninth as Perdomo doubled for his second RBI of the game and Corbin Carroll had a sacrifice fly.