Byrnes had started all 21 of the club's games before Thursday, when he sat out and revealed that he has been bothered by what he termed "leg issues" since the beginning of Spring Training.
Partially because the team has a day game Saturday following Friday's night game, Arizona manager Bob Melvin decided to give Byrnes another day.
"As far as I'm concerned, he's in there [Saturday]," Melvin said.
That's music to the ears of Byrnes, who likes to be out of the lineup about as much as most people like getting a root canal.
"If it were up to me, I probably would have played [Thursday], which is why it's good I'm not a player-manager," Byrnes said. "I think it's just a day-to-day thing. I'd like to think I'll be back in there tomorrow. It feels a little better. A couple of days are only going to help."
The injury, which apparently involves both of his hamstrings, likely will not heal until he's able to take a prolonged rest -- and that won't happen until the end of the season. Byrnes said he accepts that he will have to play the rest of the season with discomfort.
In an attempt to help him get better quickly, Byrnes is using a Advanced Recovery Performance Machine that he had previously purchased. The machine delivers a bio-electrical current to the injured area and is different from the traditional electrical stimulation treatment.
"It's painful," Byrnes said of the treatment which has been used by some NFL players, including Arizona Cardinals wide receiver Larry Fitzgerald.
Steve Gilbert is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.