"It took a lot for me," said Machado, who has no history of back issues. "I was out there, and tried running more sprints to see if it was going to go away. But it kept getting tighter and tighter. I really didn't want to, but it was best for the team. In the situation I was at, I wasn't going to be able to be an elite player and help the team win. It was a better situation for me and the team."
Machado was replaced at third base by Ryan Flaherty, who moved down to the eighth spot in the batting order. Second baseman Jonathan Schoop moved up from ninth to Machado's original spot at seventh, with catcher Caleb Joseph moving down to hit last.
"[Machado] walked over to me and said, 'Skip, I don't think I can go.' and I looked and said, 'Are you serious?' We were ready to take out the lineup card," said manager Buck Showalter, who debated on moving first baseman Chris Davis over to third to keep Steve Pearce starting. "Talk about pressure to come up with a lineup."
While Showalter should have more time on Wednesday, it's unclear whether Machado will be back after just a one-day reprieve.
"We saw a doctor and he said it just spasm'ed up a little bit," said Machado, who had no plans Tuesday for an X-ray or MRI. "Took some pills and hopefully it gets better with some time. We'll see how it feels tomorrow."
Added Showalter: "I'll feel a whole lot better [Wednesday] if it manages itself. It's the old day to day."
Machado has played in 66 games for Baltimore this season, missing the first month recovering from offseason knee surgery and recently serving a five-game suspension. He also missed a couple games with a right groin injury in May.
Machado entered the day batting .267 with 10 homers and 23 RBIs.
Brittany Ghiroli is a reporter for MLB.com. Read her blog, Britt's Bird Watch, and follow her on Facebook and Twitter @britt_ghiroli. This story was not subject to the approval of Major League Baseball or its clubs.