To make room for Pena on the 25-man roster, Tampa Bay sent infielder Ben Zobrist to Triple-A Durham.
"[Maddon is] a really smart guy," Pena said. "I trust his judgment. His whole thing is, come back and kind of ease back into it. Obviously, we're playing great baseball. We want to keep things rolling as it is without making too many changes. With time it should keep getting better and better and better."
Pena's and shortstop Jason Bartlett's respective returns to the lineup help bring stability to the Rays' infield. Pena has been out since June 3 with a broken left index finger, while Bartlett has missed the last two games because of the birth of his first child.
In his rehab stint on Thursday, Pena went 0-for-4 with an RBI and a walk as the designated hitter for Class A Vero Beach.
The slugging first baseman will wear a protective padding outside of his left batting glove to help ease impact. He was seen testing out the padding by swinging a bat in the clubhouse before Friday's game.
"I'd much rather back off for a little bit and get him reabsorbed through the lineup," Maddon said. "It's just to get him going again, get his timing, get comfortable and then we'll move him right back to the four spot."
The Rays are more worried about Pena's ability to throw than anything else. Maddon said that once the Rays return to American League play, he might consider putting Pena at DH to help ease the workload on his left index finger.
"He's going to feel some soreness," Maddon said. "That's not going to go away overnight. For right now, he seems to be fine. We're looking forward to having him back."
As for Zobrist, the 27-year-old made the most of his second stay with the Rays in 2008. He homered in two straight games against the Marlins on June 25-26, and scored three runs.
"I think that's what I was here to do -- kind of fill in while Bartlett was gone," Zobrist said. "I feel like I did my job. Hopefully, I get the call next time when they need somebody.
"I feel like I'm progressing as a hitter," he added. "It's a reality check about the game that you don't hear about. Unless I get some big break, it's going to be like this for the next year and a half, so I've got to get used to be playing wherever, whenever."