CHICAGO -- The Cubs are in need of a fifth starter, but then again, they may not be.

Brett Anderson was placed on the 10-day disabled list on Sunday because of a low back strain, creating an opening in the rotation. However, with an off-day on Thursday, the Cubs could go with four starters and not have anyone pitch on short rest.

They do have two options to fill Anderson's spot: Mike Montgomery, who is in the bullpen now, and Eddie Butler, who is at Triple-A Iowa.

"We're considering both options," manager Joe Maddon said Sunday about inserting someone or just going with a four-man rotation. "We haven't committed to anything yet, except that it would be one of those two guys."

After Sunday's game against the Yankees, the Cubs have a three-game series against the Rockies in Denver, and Maddon said they want to see how that goes before deciding. Butler started on Saturday night for Iowa and would be able to pitch Friday against the Cardinals, which would've been Anderson's next scheduled start.

Montgomery has appeared in 11 games, and his longest outing was 3 2/3 innings against the Phillies on May 1, when he threw 52 pitches.

The Cubs began Sunday still in first place in the National League Central despite the rotation not being as sharp as one year ago.

"Starting pitching drives the engine," Maddon said. "As we pitch better, we'll play better."

Worth noting

• Outfielder Jason Heyward did not start for the second straight game on Sunday because of a sore right knuckle injured when he was diving for a ball on Friday. before the game, Maddon said Heyward was available to play defense but wasn't sure if he could hit. Apparently, Heyward wasn't available because the Cubs didn't use him in the 18-inning game Sunday.

"He was down," Maddon said. "We have to evaluate it to see moving forward. We played that entire game with three extra players."

• Cubs players found out about Matthew Szczur being designated for assignment less than one hour before Saturday's game. It was tough to say goodbye to the outfielder.

"It's the best thing for Matt," Anthony Rizzo said. "He loved being a Cub, and he embodied what being a Cub was all about. He wasn't selfish at all and knew his role. He came in every day with a good positive attitude."

The Cubs have seven days to either place Szczur on waivers, trade him or release him. He was expected to draw interest from other teams.

• The expectations are high for the Cubs this season, and the team hasn't gotten off to as quick a start as it did last year. Maddon was asked Sunday how he stays so calm.

"I read the newspapers; I read the front pages," he said. "I have kids, grandkids. I have a foundation and we deal with a lot of people in very difficult situations. I see our guys do it daily. At the end of the day, it's a game. I want to win as badly as anybody and I hate when we lose, and I do carry it home sometimes.

"Let's evaluate exactly what's going on here -- let's not get carried away. Hyperbole has no place here, but it has a tendency to creep in. For me, really, understand exactly what's going on and don't exaggerate your plight. What's going on? We should've won the first game [on Friday], and we did not. It should've been a four-game winning streak. Last night was a bad start. That's not any reason to blow anything up for me."

Which means Maddon has a much calmer demeanor than most Cubs fans.

"Believe me, I get upset," he said. "I don't like when we lose. ... But at the end of the day, it is a game."

• On Sunday, fans in the Wrigley Field bleachers wore bright pink tees as part of Advocate Health Care's "Pink Out" to promote breast cancer prevention awareness while celebrating women everywhere who are survivors. Breast cancer survivors participated in ceremonial first pitches, singing the national anthem, forming a symbolic pink ribbon around the pitcher's mound and leading the seventh-inning stretch.

The Cubs will be on the road when MLB honors breast cancer awareness on Mother's Day.