When you first heard about J.D. Martinez’s back spasms you had to wonder — would this be one of those nagging injuries that could perhaps hold down his production?

So when he blasted a two-run homer into the Red Sox bullpen in the fifth inning to break a 2-2 tie in Boston’s 4-2 win over the White Sox Saturday, you had to breathe a sigh of relief if you were a Red Sox fan and a teammate. He had missed a couple of games with back spasms, including Friday night when Chris Sale lost a 1-0 decision. If Martinez could have played in that game, who knows if the results would have been different.

Red Sox manager Alex Cora didn’t seem overly concerned about the back spasms.

But if there was reason for concern, you have to understand how important Martinez is to the Red Sox lineup. He’s a game-changer, and the Red Sox didn’t want to see Martinez lose significant time, especially with Mookie Betts on the disabled list.

And Cora offered up another reason — Martinez has become a team leader. Lately, Martinez has been taking Rafael Devers under his wing and trying to teach him how to hit and think. Devers has struggled for a while, but Cora hopes that Devers and others will stay patient with the Martinez approach.

“There are a few sore arms on the coaching staff,’’ quipped Cora about the amount of extra hitting Martinez puts in. “There’s plenty of ice after the games. He understands hitting. In the past few weeks, he’s taken charge. I hope they’re patient with him. They might not see results right away but when it clicks it’ll be well worth it. He was helping out Raffy. There’s no language barrier there. We signed him to do what he’s doing offensively but there are other things at play when you sign a contract like that.’’

Martinez came into 2018 as a guy who hadn’t played many full seasons. He played 158 games in 2015 and hit 38 homers and knocked in 102 runs. Last season he played in 119 games with the Tigers and Diamondbacks but still managed 45 homers and 104 RBIs. He played in 120 games in 2016 for the Tigers. So there was an injury history there.

But Martinez was back in the lineup Saturday, DHing and hitting third. He had grounded into a fielder’s choice in his first at-bat and struck out in his second against lefty starter Carlos Rodon. But in his third at-bat, in the fifth, he hit one of his classic homers — to right field. In the seventh he singled sharply to left.

Martinez has 21 homers and 54 RBIs, both major-league bests, and former Tigers teammate David Price said that he’s seen him even hotter than he’s been.

Martinez is also starting to put himself in the top echelon of Red Sox power hitters. The Sox’ record for the most homers through June is 24, held by Ted Williams (1950), Mo Vaughn (1996), Jose Canseco (1996), and Manny Ramirez (2001). When David Ortiz set the Red Sox’ single-season home run record of 54 in 2006, he hit 23 through June.

When you watch Martinez hit homers and see the Red Sox ranking second in the majors with 95 homers, you wonder how they managed to win 93 games ranking 27th with the long ball last season. The quick-strike offense that Martinez has provided has been everything the doctor ordered.

It also allowed the Red Sox to reward Price with a win Saturday after he’d allowed two first-inning runs and became engulfed in a 2-2 game through four innings.

Jackie Bradley Jr. also homered, tying the game in the second inning. Until Martinez put the Sox ahead, it was another frustrating day against a sub-.500 opponent.

Price got better after the first. Martinez bailed them out and all ended well. With the Yankees entering Saturday with three fewer losses, the Red Sox needed to take advantage of this portion of the schedule, including three games in Baltimore starting Monday.

Keeping Martinez healthy is hugely important. Martinez has always been a workaholic in terms of extra hitting and an extraordinary amount of time in the batting cage, which by the sound of it he hasn’t backed off. After going 0 for 2 against Rodon, he returned to the batting cages and worked on what he thought he was doing wrong.

“I felt early in the game I was jumping off my backside and I went into the cages and concentrated on staying on my backside and not jumping off it. I expect myself to do well. That’s the competitor in me. That’s the confidence I have when I’m hitting well.’’

Martinez hit a changeup for the home run.

After the game he seemed to be feeling OK.

“It’s kind of one of those things that [the back] got tight in Houston. I tried to push through it with Mookie out. If I could fight through it, I fought through it. I had the day off yesterday and it felt better today. It’s just one of those things,’’ he said.

One of those things that the Red Sox can’t allow to get worse. Martinez now has a major league-best eight game-winning home runs and that, in a nutshell, is the reason he needs to stay healthy.

Nick Cafardo can be reached at cafardo@globe.com. Follow him on Twitter @nickcafardo.