By Bruce Levine-

(CBS)  A return by their top run producer from an injured back was just the medicine the struggling Cubs offense needed Monday night.

Chicago welcomed back first baseman Anthony Rizzo to its lineup after an 18-game absence, and the team’s top power hitter hit a walk-off ninth-inning homer to give the Cubs a 1-0 win against the Reds at Wrigley Field. Rizzo had been out of commission with a lower back issue since Aug. 26,

With the game on the line, Rizzo was trying to knock the rust off after three less-than-satisfactory at-bats.

“The first three at-bats, I was swinging at pitches that were bouncing,” Rizzo said. “There is not a better feeling (than a walk-off home run). The game is over with one swing of the bat. The biggest thing is the win.”

After hitting his 30th home run against the Reds back in August, Rizzo was in rehab mode until Monday evening.

Over the past three weeks, Chicago has produced mostly poor offensive outputs, with Rizzo and shortstop Starln Castro (high ankle sprain) out of the lineup. The Cubs’ record was 6-12 while Rizzo was out.

Before Monday night, Chicago had scored 22 runs in its last nine games while losing eight of nine.

“We knew there wasn’t any reason to rush back,” Rizzo said. “I am not chasing anything like ‘x’ home runs or RBIs. It is good to be back healthy, and I am just going to enjoy this evening.”

Rizzo won’t play every day the rest of the way, according to manager Rickey Renteria.

“He actually told me he was fine on Friday in Pittsburgh,” Renteria said. “We spoke on Sunday, which was a heart-to-heart conversation in terms of making sure that he was really doing well. We are pretty confident he is doing well. It has been almost three weeks of not playing on a daily basis, so we will take it day to day.”

Leadership roles are earned but never given to young, evolving players. Rizzo and Castro have had to take the reins of this young Cubs team and improvise as leaders with so many veteran players having been traded the last three seasons. Because of that, the two 24-year-old position players have developed skills on and off the field.

“We are all accountable for what goes on the field, in the clubhouse and before the game,” Rizzo said. “If someone isn’t living up to expectations of what we believe is right, someone is going to get on them. Whether it is me, Castro, Weli (Castillo) or one of the pitchers, someone will get on someone to send a message. At the end of the day, it’s all about how are we going to win today.”

The Cubs’ top baseball executives are happy with the progress of both Castro and Rizzo. Putting the burden of leadership on their shoulders may be asking a lot at this early juncture of their careers, but that’s what they’ve been called to do.

“Looking at this time without the two of them in the lineup kind of established what they mean to our team,” Cubs general manager Jed Hoyer said. “It was tough sledding for the six or seven games we did not have both guys. I think both want to be leaders. I think both are in the process of learning how to do it. They probably need some guys around them that can teach them the right things to do. I think in time, they will grow into that role. Right now, I don’t think they have enough experience or been around enough guys that are real clubhouse leaders. We need to provide that for those guys.”

Rizzo struck out against Reds starter Alfredo Simon in his first two at-bats Monday. He was given a generous infield hit on a simple ground ball in his third at-bat after it was thrown in the dirt to first in the sixth inning.

Rizzo was a first-time All-Star in 2014, and he became only the seventh Cubs left-handed hitter in franchise history to hit 30 or more home runs in a season. Rizzo is also the first to do it since Fred McGriff hit 30 in 2002.

Chicago starter Travis Wood threw six shutout innings in a no-decision. He sees a leader in the making in Rizzo.

“We have definitely been missing their presence,” Wood said of Rizzo and Castro. “Rizzo really showed that tonight with his first game back. He scuffled there in his first couple of at-bats before that one. That is what baseball is all about, being able to salvage a night, and he came up big.”

Bruce Levine covers the Cubs and White Sox for 670 The Score and CBSChicago.com. Follow him on Twitter @MLBBruceLevine.