The Boston Red Sox on Monday agreed to a three-year, $39 million contract with free-agent first baseman/catcher Mike Napoli, pending a physical, a baseball source with direct knowledge of the negotiations told ESPNDallas.com.

Napoli, who visited Boston late last month, is expected to play primarily at first base for the Red Sox.

Napoli's physical will take place Wednesday, a source said, and his signing likely will be announced at week's end.

He was identified early on as a logical target to fill the Red Sox's need at first and gives the club another option behind the plate if general manager Ben Cherington elects to shop Jarrod Saltalamacchia at the winter meetings. But Saltalamacchia sounded confident Saturday that he is very much a part of the team's plans moving forward, and a baseball source said Monday that he has gotten no indication that the Red Sox intend to move Saltalamacchia.

"We've made some progress," Cherington said regarding the potential Napoli deal. "He's a guy who's getting on base, has power and could be a good fit for our ballpark. We knew when we made the Dodger trade, when we moved (Adrian) Gonzalez, that we would have to try to find a way to replace that offense, and as we got into the offseason we understood that was probably going to have to come from a combination of guys and maybe not one guy.

"He can catch and he can play first. If he's here, I would imagine he'd do some of both but that would be up to our manager to figure out."

Napoli has never played more than 70 games at first base, which he did in 2010, when the Angels' Kendrys Morales fractured his leg in a freak accident and Napoli was pressed into duty as a replacement.

"It is my expectation that he is going to be a right-handed power bat in the middle of their lineup," Napoli's agent, Brian Grieper, said Monday. "As far as position, that is up to the Red Sox."

This past season, Napoli caught 72 games for the Rangers, but the most he has caught in his career is 96 games (2009), and at age 31, he might be receptive to making a more permanent position switch to first base.

"I just want to play," Napoli recently told ESPNDallas.com. "I feel the most comfortable behind the plate because that's where most of my reps have been. Do I think I can be good at first base if I had reps and practiced it all the time? Yes. But it's not like I'm saying I have to be a catcher. I just want to be in the lineup and play. If it helps at catcher, I'll catch, or at first base, I'll play there. But I like catching. I look at myself as catcher."

Red Sox pitcher John Lackey, a teammate of Napoli's with the Angels, led the recruiting process to lure Napoli to Boston.

"I've been working on him and I had a couple of guys text him," Lackey told ESPNBoston.com. "We've been recruiting him the last few weeks, so I'm glad things worked out and we got him. He's going to be a great addition to the club."

Lackey and Napoli played together for four seasons and the veteran pitcher made sure to push the fact that there's a good group of players in the Red Sox clubhouse and Napoli's presence would only help solidify the type of character the team is trying to build.

"We talked about the guys on the team and I told him how great of a group of guys we have on the team," Lackey said. "I had (Jon) Lester and (Dustin Pedroia) texting him and kind of recruiting him too. Those guys were getting in his ear, trying to convince him to come to Boston. Ben and those guys did a great job and they obviously put together an offer that he liked. It's going to be fun.

"He's fun. He's a guy who likes to have a good time, but when it's time to go he's ready to compete. He's not going to be scared about anything."

The Rangers also met with Napoli and had interest in bringing him back, but they did not make a qualifying offer of $13.3 million, which means Boston could sign him without forfeiting a draft choice.

Napoli would give the Red Sox a needed right-handed power bat, especially if the club is unable to retain outfielder Cody Ross, which will be the case if Ross is able to persuade another team to sign him to the three-year deal he was unable to score last winter.