BOSTON — The walk-off hit from Rob Refsnyder that delivered the Red Sox a 5-4 win over the Rangers in 10 innings on Monday night was badly needed for a team that had been teetering a bit in recent days due to a variety of reasons.

But the walk that helped set up Refnsyder’s rocket single to the base of the wall in left-center was in the storybook category because of the man who authored it.

Meet Mickey Gasper, the 28-year-old who had spent the past six seasons in the Minor Leagues before getting his first call-up to the Majors earlier in the day.

This was a moment Gasper likely dreamt about while growing up in Merrimack, N.H. Something perhaps he envisioned while playing college baseball at Bryant (in Smithfield, R.I.).

Or maybe Gasper thought it would come in the Bronx instead of Fenway, considering he was in the Yankees’ farm system from 2018-24.

When the call finally did come on Monday, Gasper had one thought: Time to drive fast.

At around 2:30 p.m. ET, Gasper was in Worcester, Mass., — the site of Boston’s Triple-A affiliate — when he suddenly learned he had to get 50 miles east to Fenway Park.

Mondays are always off-days in the Minors. This one ended excitedly for Gasper.

“It was late. I got my hair cut, went grocery shopping,” said Gasper. “I was going to cook a little bit. I was just getting comfy, and [Worcester manager] Chad Tracy called me up, and let me know.”

Late into the night on Monday, Red Sox manager Alex Cora made it known to Gasper that it was time to hit. Boston had just tied the game on an RBI double by Enmanuel Valdez to lead off the inning, and Nick Sogard kept the traffic on the bases going with a single.

Following a fielder’s choice by Ceddanne Rafaela, Rangers manager Bruce Bochy went to lefty reliever Walter Pennington.

That meant it was showtime for the switch-hitting Gasper, who was called on to hit for the left-handed-hitting David Hamilton.

Down 1-2 in the count, Gasper worked a seven-pitch walk that loaded the bases with one out and put the Red Sox on the doorstep of a win that would end a four-game losing streak and slim the deficit to the Royals in the American League Wild Card race to two games.

With two outs, Refsnyder sent everyone home with one of the biggest hits of the season for the Red Sox.

But Refsnyder isn’t the one who got the beer shower in a joyous clubhouse.

“A lot of the credit goes to [Gasper],” Refsnyder said. “That was a huge at-bat. We gave him a beer shower to celebrate his debut and it was just a fantastic job by him.”

This wasn’t just some case of a journeyman getting called up because a team was in a pinch. Gasper earned every bit of the promotion. After he vaulted from Double-A Portland to Worcester in June, Gasper slashed .401/.515/.664 with eight homers and 32 RBIs in 40 games. Needless to say, he came to Fenway on a heater.

And even if there were plenty of Red Sox fans who had never heard of Gasper until he stepped up with the game on the line on Monday, he never had a doubt his MLB debut would come at some point.

“I’ve always thought the big leagues were realistic. People told me that I’m a big league hitter before,” said Gasper. “Anything short of the big leagues just didn’t seem like a possibility for me.”

Strangely, Gasper didn’t feel nervous when that long-awaited first Major League plate appearance presented itself.

“I was so calm up there,” said Gasper. “I guess I felt like I was at home. I don’t know. I was relaxed. Saw the first couple pitches, was a little upset he dotted that stinker on me. That was a good pitch to hit. But it’s all right. I moved on, just kept my breathing, stayed composed, and had some fun up there.”

To be truthful, the hours leading up to the game weren’t much fun for the Red Sox.

The move to call up Gasper was to fill the roster spot vacated by All-Star Jarren Duran, who was suspended for two games by the Sox for making a homophobic remark to a heckling fan. And Refsnyder got a rare start against a righty starter due to Duran’s absence.

After a difficult day, the Red Sox got a win they needed. And the winning hit was delivered by one of the team’s consummate professionals.

“He’s a grinder, and he’s one of the leaders of the team,” Cora said of Refsnyder. “He was patient, got a good pitch to hit and finished it off. We needed to finish the game at that point.”