First baseman Anthony Rizzo returned to the lineup Saturday against the Brewers after missing five games because of tightness in his back.

Jonathan Lucroy pinch-hit for Rizzo in the fifth inning last Saturday against the Nationals, and he hadn’t played since. He said his back “grabbed” him while he was running.

Rizzo had a lot of treatment done and did some stretching the last few days.

“I got it to just calm down and hope to have fun the next month,” Rizzo said.

Back ailments have become a recurring issue for Rizzo, who missed four games in May and also went on the injured list in the spring of 2018 with lower-back tightness.

Manager Joe Maddon said he traded texts with Rizzo, who relayed that he wanted to get back in the lineup. Rizzo swung a lot Friday and felt good Saturday, which Maddon called a “big litmus test.”

It’s that day

Sunday is Sept. 1, which means rosters can expand. Ben Zobrist will be one of a handful of players to join the Cubs, and Maddon said there could be five or six additions.

In the past, Maddon hasn’t appeared to be the biggest fan of the roster inflations. But his tone has softened somewhat.

“I’m not [a fan], but then again, when you need it, it’s kind of interesting to have,” Maddon said. “It’s always about rest. I always consider that.

‘‘So when you have enough guys on the bench, you can get out all the pertinent players. Otherwise during the regular season, I’ve got to make choices regarding who needs that extra moment.”

The glut of players allows managers to play matchups even more or insert a player for a timely stolen base.

Maddon also likes having extra catchers and the ability to pinch-hit freely.

Next year, things will change. The regular roster will rise to 26 players, and from Sept. 1 on, teams will carry 28.

Slamming the bat

After launching his home run in the second inning Friday, right fielder Nick Castellanos slammed his bat into the ground with both hands. The Brewers had a problem with the moment, but it wasn’t anything Castellanos did.

“Hitters are going to do what they’re going to do,” Brewers right-hander Chase Anderson told reporters Friday. “You make better pitches and you get them out, they don’t do that stuff.”

Maddon didn’t have an issue, either.

“He reacts to the moment,” Maddon said.

“He’s always got these visceral reactions that I really enjoy, and I think the rest of the team feels it.”

Hamels’ improvement

Left-hander Cole Hamels came into the game with a 9.56 ERA in his previous four starts but recovered from a two-run first to work six innings and allow only five hits.

Recently, Hamels’ mechanics had been off, and he had been working to get back on track.

“Day after day, I’m really just putting in the time and the effort and making sure that I can figure some things out and find any sort of flaw that I have and address it,” Hamels said, “and then just get the reps.”