CHICAGO -- Anthony Rizzo's back wasn't loosening up, so the Cubs placed the first baseman on the 10-day disabled list Tuesday, retroactive to Friday.
"It stinks, especially to not be able to play the home opener," Rizzo said Tuesday. "It's a long season, it's a marathon and you have to stay smart, and that's what we're doing."
Rizzo, who had never been on the DL before, has missed the Cubs' past three games and was not in the lineup for Monday's scheduled home opener because of tightness in his lower back. If all goes well, Rizzo would be eligible to play Monday against the Cardinals.
It was warmer on Tuesday than Monday, when the Cubs' home opener was postponed because of snow. That doesn't matter, Rizzo said.
"I think if it was 80 degrees right now or 20, it doesn't matter," he said. "It's right to get it better for the long haul."
Rizzo has had back issues in the past, but usually later in the season.
"Usually it's July, August, September," he said. "You mentally grind through it, and as long as you can move, you can play. This is one of those things where we talked and I don't want to be locked up for the entire year."
Benjamin Zobrist started at first base on Tuesday and the Cubs called up first baseman Efren Navarro from Triple-A Iowa. Navarro, 31, played parts of five Major League seasons with the Angels and Tigers.
"I talked to [Rizzo] yesterday in the training room, and he's going through a myriad of exercises and you could see he wasn't 100 percent comfortable," manager Joe Maddon said. "Let's not rush it. I really believe he'll be fine at the conclusion of this DL stint."
Rizzo said he felt some discomfort one week ago when the Cubs were in Cincinnati, and got a break when the April 3 game was postponed because of rain. He did play Thursday in Milwaukee, but his back locked up again.
"I think the next time I go [to Cincinnati], I'll sleep on the floor," Rizzo said. "I just have to take care of myself better."
That means more core exercises for the first baseman. One thing Maddon would like to see is Rizzo taking fewer swings in batting practice.
"I still believe guys swing too much," Maddon said. "I came here this morning and I'm hearing cracks of the bat down the hallways in the batting cage. I don't think Billy [Williams] did that, I don't think [Ron] Santo did that, I don't think Ernie [Banks] did that. They probably didn't have a batting cage to do that in.
"With Anthony, I'm trying to convince him to back off -- no pun intended -- a little bit, because swinging too often can exaggerate the issue," Maddon said. "If more swings were the answer, everybody would hit .300."