Percival has been slowed by left hamstring problems all year and has made it no secret that he has not been 100 percent since his return from the disabled list on June 13.
"It's not tearing, I don't know if it's nerve or what," he said. "I don't know what it is, but it just keeps going and going. It's been like this every outing. I've just had to deal with it. But covering third and covering home was more than it could take."
When Red Sox catcher Jason Varitek hit a sacrifice fly for the inning's second out, Navarro noticed Percival limping and quickly sought to address the situation.
"He's fiery," Navarro said. "He wants to go out there; he wants to be part of this team so bad. It was just the right decision. ... We've still got 80 games to go."
After the game, Percival acknowledged that the shouting match on the mound was more of an airing of frustrations than a grudge against Maddon.
"I knew Joe was doing the right thing, I knew it at the time," Percival said. "I was frustrated about the ring [double off the catwalk] shot. I was frustrated that my leg just popped again for the 12th time. And I just needed to yell at somebody, and he was there."
Percival added that he apologized immediately to Maddon and was grateful that the Rays skipper "knows me better than any coach can know a player."
Maddon was equally submissive about the discussion on the mound, citing his close relationship to Percival that stems back to the time they spent with the Angels' organization.
"This guy has done this for years," Maddon said. "He's trained to be the last guy out there; he's a very accountable person."
Entering Monday night, Percival was 19-for-21 in save opportunities and was holding opponents to a .135 average, the second-lowest in the American League.
Although another trip to the disabled list is a possibility, Percival was hesitant to comply.
"It's not something I want to think about until [Tuesday], to be honest with you," he said. "There has been nights when I threw my inning no problem, and I've come in here and said, 'There's no way I'll be able to go out tomorrow,' and then it's not that bad."
Either way, Percival is not expected to be available for Tuesday night's game. Neither is Dan Wheeler, the Rays' regular eighth-inning setup man, as he has pitched the past three nights.
Howell -- who said he entered Monday's game with the singular focus of recording the out for Percival -- could be used in the later innings, as could Grant Balfour, who threw two-thirds of an inning on Monday.
"I can't lie. It's something, obviously, a position I'd love to take," Balfour said. "It's something, as a reliever, it's the spot you want to be in. And you work your way toward that. If I get that opportunity, I'll take it with both hands."