CHICAGO -- The past couple of weeks have been hectic for Mike Montgomery and his family. Not only has the Cubs pitcher been working his way back from a left lat injury -- with another Minor League rehab assignment around the corner -- but he and his wife welcomed a son into their arms on Tuesday.

Montgomery laughed when asked if he has placed a baseball in little Max's left hand yet.

"No, but I'm working on that," Montgomery said with a smile, before Sunday's 2-1 walk-off victory. "I've talked to the doctors to try to figure out how to make him left-handed."

Montgomery added that the "whirlwind" experience has offered him renewed perspective on what is important, which includes getting healthy so he can again impact the Cubs' pitching staff and provide for his growing family. The next step for the lefty (on the 10-day injured list since April 6) will be a Minor League rehab appearance with Double-A Tennessee on Monday.

Montgomery said the plan calls for three innings for the Smokies. That will come after he logged 27 pitches in a two-inning appearance for South Bend (Class A) on Wednesday.

In the early portion of Spring Training, Montomery experienced left shoulder tightness and had his Cactus League debut delayed until March 12. The lefty broke camp with the Cubs, but struggled in his first four outings (six earned runs allowed on eight hits in 2 2/3 innings) before being shelved with the lat issue. Lately, Montgomery said his improved physical condition has allowed him to focus on things he could not work on during his abbreviated spring.

"I kind of feel like I've always been playing catch-up so far this year," Montgomery said. "I haven't been able to get out there and really work on certain pitches to certain zones. Working on my cutter, slider -- getting that a little sharper. Working on my curveball command to where I can throw it early in the counts or bounce it. That's kind of been missing.

"So, the last week or so, I've gotten back to that. I threw a bullpen the other day and really worked on some stuff that I hadn't been able to do. That's a good thing for me. That will kind of put me in the best position to be successful."

Mills added to bullpen

Prior to Sunday's game against the D-backs, the Cubs optioned left-hander Randy Rosario to Triple-A Iowa and recalled righty Alec Mills from the same affiliate. Mills worked four innings for Iowa on Wednesday and gives Chicago an arm capable of handling multiple innings.

Mills, 27, posted a 4.00 ERA in 18 innings with the Cubs last season, but spent the bulk of the year with Triple-A. With Iowa in '18, the righty had a 4.84 ERA in 23 starts (124 2/3 innings). Mills was limited to five innings for Chicago during Spring Training due to a back issue.

Worth noting

• Maddon noted that veteran lefty Jon Lester was "doing well" on Sunday, following a three-inning simulated game on Saturday. The Cubs have not yet announced the next step for Lester (10-day injured list, left hamstring), but the team currently has not announced a starter for Thursday's game against the Dodgers. Barring any setbacks, it is possible Lester could be activated for that start.

• Left-hander Xavier Cedeno (10-day IL, left wrist) worked one-third of an inning for Double-A Tennessee on Saturday, issuing two walks with one strikeout and no runs or hits allowed. The next step for Cedeno has not been announced yet by the club.

• Right-hander Tony Barnette (10-day IL, right shoulder) was scheduled to begin a Minor League rehab assignment with Triple-A Iowa on Sunday.

Umps Care auction underway

The 11th annual Umps Care Charities auction has started with more than 400 items available. The auction, which included an autographed bat from Cubs utility man Ben Zobrist, will run through 9 p.m. CT on April 29. All proceeds from the online auction support the Umps Care Charities youth program.

"The auction has something for everyone," Gary Darling, who served as an MLB umpire for nearly three decades and now serves as board president for Umps Care Charities, said in a statement. "From autographed memorabilia to once-in-a-lifetime experiences. So we encourage fans to tell all of their friends and family to check out the available items on MLB.com and bid generously to help support a great cause."