Jennings had lower-back pain and missed his first game Saturday against the Rangers. Since then, he has felt better each day.
"He felt really good [Wednesday], did a lot of swinging earlier," Maddon said. "He should definitely be able to pinch-hit tonight if needed. Plan to play tomorrow, not 100 percent sure of that, but I think he'll play tomorrow, and he is available tonight."
Maddon confessed to being "overcautious on our part."
"It's one of those things where he said he feels good, he can play, let's wait one more day," Maddon said.
Maddon was asked if Jennings had been out longer than expected, and he answered, "Not really."
"[Head athletic trainer Ron Porterfield has] been telling me, maybe he'd miss all of [the] Baltimore [series]," Maddon said. "Just keep calling it day to day. It just is what it is."
Maddon said the main thing he was concerned about was pushing Jennings and then losing him for a substantial period of time.
"So let's just be cautious," Maddon said. "I like the way Ronnie's handled it. And I think he should be able to start again starting tomorrow."
Maddon wants Jennings to be 100 percent, and that stance was easier to take because Maddon said the Rays have been covered the first two games of the Baltimore series.
"We played these guys yesterday and today, obviously, and the way their pitchers line up vs. our offensive players, we're kind of covered, and we're covered in the position also," Maddon said. "So it wasn't a real urgency to get him back out there. I feel good about Ben [Francisco] out there. I would have felt good about putting Sam [Fuld] out there. But based on the pitching matchups, I wanted to go with Ben yesterday and today."