PHOENIX — The Rangers went from a graybeard to Gray on Monday in reclaiming the World Series lead.

Max Scherzer’s latest malady is back spasms, an ailment that ended his night after three scoreless innings, but the Rangers were fortunate to have a solid reinforcement in waiting.

Jon Gray, previously a candidate to start Tuesday, emerged from the Rangers’ bullpen and delivered three scoreless innings in the team’s 3-1 victory over the Diamondbacks in Game 3 of the World Series at Chase Field.

In taking a 2-1 lead in this best-of-seven series, the Rangers established a major league record with their ninth straight road victory to begin a postseason.

The 39-year-old Scherzer had back issues earlier this season that forced the Mets to push him back in the rotation at least once, but never sent him to the injured list.

He also incurred neck spasms in May that pushed him back a start.

Scherzer had a strained teres major muscle near his shoulder late in the season that landed him on the IL and forced him to miss the ALDS.

This time Scherzer said he felt his back starting to spasm on a slider he threw to Evan Longoria in the third inning.

By the start of the next inning the back had completely tightened.

“It’s frustrating as heck, but that is the hand I’m dealt so I have got to deal with it,” said Scherzer, who said he probably won’t know before Wednesday if he will be in position to pitch later in the series. “We feel we have got a good beat on what this is and how to treat it.”

If Scherzer’s early departure wasn’t enough, the Rangers also watched Adolis Garcia (and his MLB record 22 RBIs this postseason) depart in the eighth inning with left side tightness.

He will receive further testing on Tuesday.

Gray kept the Rangers afloat by pitching three scoreless innings in which he allowed one hit and struck out three.

The trio of Josh Sborz, Aroldis Chapman and Jose Leclerc got the Rangers to the finish line with Chapman allowing the only run in the eighth inning.

“This is the most important time of year and to be able to contribute is a great feeling,” Gray said.

The veteran right-hander was left off the Rangers’ wild-card and ALDS rosters, but returned for the ALCS against the Astros and pitched one inning in relief.

Gray pitched 1 ²/₃ scoreless innings in Game 1 of the World Series, helping keep the Rangers close enough to rally late in their 6-5 victory in 11 innings.

“I feel like I have been taking care of everything the right way and this is a good reward,” Gray said.

Scherzer’s abbreviated outing followed two shortened starts against the Astros in the ALCS in which he was ineffective.

Christian Walker was thrown out at the plate in the second inning after getting a late read on Tommy Pham’s single to right.

Walker, who had doubled leading off the inning against Scherzer, was easily tagged out by catcher Jonah Helm on a strong throw from Garcia.

Scherzer escaped the inning on Alek Thomas’ shot that ricocheted off the pitcher to third baseman Josh Jung to start a 1-5-3 double play.

Scherzer walked Corbin Carroll with two outs in the third and threw a wild pitch before retiring Ketel Marte.

But after returning to the mound for the fourth and throwing a warm-up pitch, Scherzer exited with the team trainer.

Corey Seager’s two-run homer in the third was the big hit in an inning the Rangers scored three times to grab a 3-0 lead.

Nathaniel Lowe doubled leading off the inning and with two outs scuffling Marcus Semien delivered an RBI single.

D’backs pitching coach Brent Strom had barely returned to the dugout from his mound visit with Brandon Pfaadt before Seager launched a shot into the right-field seats for his fifth homer this postseason.

Seager most notably smashed a game-tying homer against Paul Sewald in the ninth inning of Game 1 before the Rangers won in the 11th on Garcia’s walk-off blast.

“This lineup is building off each other constantly,” Seager said.

Geraldo Perdomo’s RBI single in the eighth got the D’backs a run against Chapman.

But after Carroll struck out, Seager’s diving stop on Marte’s grounder initiated a highlight-reel double play.

The offensive shutdown came after the D’backs scored nine runs in their Game 2 victory in Texas.

“I thought we had a good approach against Scherzer,” D’backs manager Torey Lovullo said. “And just as we were honing in on him they made a changeover to Gray. … We just got beat. We got maybe out-executed. And we’ve got to figure that out.”