This isn’t an Abbott and Costello routine: The Boston Red Sox don’t know who is going to play third base — and it’s causing tension.

Last week’s signing of Alex Bregman to a three-year, $120 million contract with deferrals was lauded as a savvy big swing that propels the Red Sox into playoff contention.

But the addition of Bregman, the American League’s reigning Gold Glove winner at third base, has been a source of contention ever since, as Boston’s incumbent at the position, Rafael Devers, isn’t interested in moving.

“I play third,” Devers, 28, said this week at spring training in Fort Myers, Fla.

“They asked me the question about how I feel about DH, and I gave them the answer that I just gave: No.”

Bregman played 995 of his 1,111 games at third base during his nine seasons with the Houston Astros, but many assumed he would move to second base with Boston.

The 30-year-old Bregman has made only nine appearances, and two starts, at second base in his MLB career but played shortstop at LSU.

But Red Sox manager Alex Cora made clear this week that the infield configuration is undecided.

“We will decide when we decide,” Cora said.

Whatever the Red Sox decide to do at third base will come with wide-reaching ramifications.

Bregman is a superior defender to Devers, who has led the American League in errors at third base in seven consecutive seasons. Devers’ -6 OAA (Outs Above Average) last season ranked in the bottom-eight percentile, according to Baseball Savant.

But Devers, a three-time All-Star, remains the face of the Red Sox and is entering the third season of an 11-year, $331 million contract.

Bregman, meanwhile, has opt-out clauses after the 2025 and 2026 seasons, meaning his stay in Boston could be as short as one season.

Moving Devers to designated hitter would displace Masataka Yoshida, who has three years and about $56 million remaining on his contract.

Moving Devers to first base would displace Triston Casas, a former first-round pick who hit 24 home runs two seasons ago and just turned 25.

“I think it’s Raffy Devers’ position,” Casas said of third base. “I think he’s the third baseman, and at that point, that’s where it stands. He’s done it for a really long time now, and I think he’s only getting better at that position. I think his defense is getting better every single year. We don’t know what the future holds, but we know it holds Raffy Devers.”

But putting Bregman at second base would not be the Red Sox’s optimal defensive arrangement.

It would also block 22-year-old phenom Kristian Campbell, whom MLB Pipeline ranks as the sport’s No. 7 prospect. Campbell hit .330 with 20 home runs, a .997 OPS and 24 stolen bases last season across three minor-league levels, including 19 games at Triple-A Worcester.

Bregman, for his part, has taken a team-first approach to the Devers situation.

“I’m super excited to just be his teammate,” Bregman said. “He’s a great player. I think everybody in this clubhouse is worried about winning, and whatever it takes to help the team win, that’s all I’m focused on. I’ll play wherever [Cora] tells me to play.”

The Red Sox went 81-81 last season, their fourth in a row without making the playoffs. The signing of Bregman marked a change in approach for a team that, in recent years, traded away Mookie Betts and Chris Sale and let Xavier Boegarts leave in free agency.

Bregman put an exclamation point on an offseason in which the Red Sox also acquired burgeoning ace Garrett Crochet in a trade with the Chicago White Sox and signed right-hander Walker Buehler to a one-year prove-it contract.

Some consider the retooled Red Sox to be the Yankees’ greatest competition in the American League East.

But the drama at third base is now something to monitor.

“Things like this happen,” Cora said. “Guys have their ideas. They’re proud. They say the things that they do, but then at the end, this is not about Alex or Raffy or [me]. It’s about the Boston Red Sox.”