Cubs’ Anthony Rizzo (back) scratched Friday, might miss Saturday, too

MILWAUKEE — First baseman Anthony Rizzo was scratched from the lineup Friday because of recurring back tightness, but the Cubs said they don’t consider it serious.

‘‘He did a lot of extra hitting [Thursday],’’ manager Joe Maddon said. ‘‘That might have brought it on a little bit. It’s definitely a day-to-day kind of thing.’’

Rizzo, who went 0-for-5 in the Cubs’ series-opening victory Thursday against the Brewers, has dealt with back tightness — typically for a day or two at a time — at least once in each of the last few seasons. He missed one game in late July last season, then returned to hit two home runs in the Cubs’ next game two days later.

‘‘We’ve been here in the past with him, so I’m not overly concerned,’’ said Maddon, who suggested Rizzo might miss the game Saturday, too.

Rizzo is off to a slow start, hitting .107 (3-for-28) with one homer.

Happ out of lineup

Leadoff hitter Ian Happ, the National League leader in strikeouts (14) entering the day, was out of the lineup against a right-hander for the first time this season. He struck out four times Thursday.

‘‘It’s called Ben Zobrist,’’ Maddon said of the switch-hitting veteran, who has started more productively than Happ. ‘‘Ian’s fine. There’s nothing wrong. Just trying to juggle all these guys in.’’

Brewers lose closer Knebel

The Brewers put closer Corey Knebel on the disabled list with a hamstring injury after he collapsed on the mound while throwing a pitch in the ninth inning Thursday. They expect him to miss about six weeks.