"I'm glad," Francona said. "He looks happy to be here, and he's ready to go, and that's good. Sometimes, when there's things to take care of, you need to take care of them."
But Kevin Youkilis, who has also been unavailable since Tuesday, was out of the lineup again, though his back has made significant progress over the past 24 hours.
"We're not going to play [Youkilis] tonight, at least not start him," Francona said. "He's much improved. He's doing a lot better."
The Red Sox also had closer Jonathan Papelbon back in the mix, after the righty missed Wednesday's game with a back injury caused by slipping in the bullpen on Tuesday.
With Jason Varitek catching Josh Beckett, Martinez started Thursday's game at first base.
Martinez, who had to fly back to Cleveland for a sensitive family matter, seemed to be in good spirits upon his return.
"I'm really happy to get back and join the team and help us keep playing good baseball," Martinez said. "You never want to leave the team, especially when you're in the middle of the race, trying to get to the playoffs. You've got to do what you've got to do sometimes."
The veteran was happy that the Red Sox allowed him to prioritize his family for a couple of days.
"Thanks to Francona and [general manager] Theo [Epstein]," said Martinez. "I talked to them, and they let me go and take care of some stuff that I had to do. It's all done. Everything is good right now. I'm ready to keep moving on and play for this team now."
Martinez, who watched both games on television, wasn't surprised that his new teammates picked him up with hard-earned wins.
"There's a lot of great hitters," he said. "Since I got here, and even playing against them, I knew that this team was able to score any amount of runs. It's just a matter of getting pitches to hit or putting good swings on balls. They know what they're doing."
Ian Browne is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.