CHICAGO -- The announcement was a part of the usual pregame routine, so the Wrigley Field crowd did not stir much when the reading of the Cubs' starting lineup began. It was not until the words sunk in that the fans began to react in an uproar of approval at the unexpected news.

"Leading off. At first base. No. 44. Anthony Rizzo."

It was only moments before that when the Cubs announced a change to their planned batting order for the opener of a critical four-game series against the Cardinals. Thought to be at risk of missing the rest of the regular season, Rizzo was back atop the lineup and at first base just five days after being hobbled by a sprained right ankle.

• Box score

And it was only three innings later that he shook the old ballpark with a game-tying blast to the left-field bleachers off Cardinals ace Jack Flaherty. In a 5-4, 10-inning loss to St. Louis, that was the only breakthrough against Flaherty, who continued his sterling second half and neutralized the early emotional lift that arrived with Rizzo's return to the diamond.

"It's tough. It's tough to swallow. This is a big weekend for us," Rizzo said. "We've got to win. We have to win games. We have to win. We fell short today, but we've got to bounce back."

The Cubs struck for three runs in an inspiring, game-tying rally in the bottom of the ninth, but Matt Carpenter’s go-ahead homer off Craig Kimbrel in the 10th sent Chicago to the loss column.

With the defeat, the Cubs dropped to four games back of the National League Central-leading Cardinals with six games remaining between the clubs within Chicago's final nine contests. The North Siders also slipped one game back of the second-place Brewers, who now have control of the NL's second Wild Card seed. The Nationals are ahead of the Cubs by two games for the top Wild Card spot.

It marks the first time since April 30 that the Cubs do not occupy a spot in the postseason picture.

• NL Central standings | Wild Card standings

"It's frustrating," said Kimbrel, who was activated from the injured list prior to the game. "I've been doing everything I can to get back out there, and our team battled to the very end. We needed that."

• Kimbrel stumbles in return from injured list

Despite the setback, the Cubs have to be excited to have Rizzo back for the stretch run.

The Knicks will always have Willis Reed, taking the court before Game 7 of the NBA Finals to the shock of fans after he was supposed to be done with a leg injury. The Cubs have Rizzo -- his right ankle heavily taped -- out in left field less than a half-hour before the first pitch on Thursday, doing running and agility drills in front of manager Joe Maddon and members of the medical team.

"Listen, all these guys want in there. Rizz wants in there," Maddon said before the game. "As they say they're ready to play, we'll play them."

It was thought that Maddon was mostly referring to Kimbrel or shortstop Javier Báez. The latter is dealing with a hairline fracture in his left thumb, but Maddon made it known before Thursday's game that Báez could pinch-run, if needed. Báez did just that in the ninth, crossing the plate as the run that pulled the game into a 4-4 deadlock.

• Báez returns as pinch-runner; hitting next?

Mentioning Rizzo felt like wishful thinking.

Things changed when Maddon returned to his office, where he was met by Cubs president of baseball operations Theo Epstein, among others. Rizzo arrived to Wrigley in a walking boot, but had ditched his supportive medical scooter on Wednesday. As the day progressed, he kept checking boxes: putting on his spikes, walking, jogging, hitting and so on.

"[They] say that Rizz is actually moving around pretty well and he wants to play," said Maddon. "I said, 'Oh, really?'"

"I just kept going, 'Wow, OK, this works. Check,'" Rizzo said. "Treadmill was fine. This was fine. This was fine. Hitting was fine. Let's tape it up. Let's put some cleats on. Fine, fine. Then, we talked risk-reward, and I think it's just, I want to play."

Rizzo sprained the ankle while charging in to field a bunt on Sunday against the Pirates, and he aggressively attacked a rehab program for the next 48 hours. Rizzo also received a cortisone shot on Monday, when the first baseman told reporters he hoped to learn more about his status within a few days.

That, too, seemed overly optimistic, given that the Cubs announced that Rizzo would remain in the medical boot for five to seven days before being re-evaluated. Maybe, just maybe, he could be ready to pinch-hit by next week's season-ending road trip. Getting ready for these home games against St. Louis seemed unlikely.

"Honestly," Rizzo said, "I did not think in a few days I'd be doing this. I had a positive mindset. I kept saying, 'It's going to take me three days. Watch. Three days.' Everyone was just kind of, 'No way.' But, I believed I was healthy and I am."

In the first inning, Rizzo walked to the plate using the signature music for The Undertaker, the superstar wrestler. The first baseman was not back from the dead, but he was back from an injury that might have kept other players out much longer.

"That was huge," Cubs starter Kyle Hendricks said. "The work he's been putting in the last few days to try to get himself back on the field has been incredible. That's the guy he is. One of our leaders. So, to have him back out there, it lifted everybody up for sure."

With two outs in the home half of the third inning, Rizzo wasted no time in getting Chicago on the board. The big first baseman slugged a first-pitch sinker from Flaherty, drilling it high over the left-center-field wall to pull the game into a 1-1 deadlock. Rizzo completed a slow trot around the bases amidst a standing ovation from his stunned audience.

Flaherty took over from there, while the Cardinals struck for four runs off Hendricks.

The St. Louis righty piled up 118 pitches over eight innings, keeping his ERA at 1.05 since the All-Star break. Flaherty struck out eight, walked one and scattered just three hits. One was the home run for Rizzo, who delivered one of the best moments of the Cubs’ 2019 season, which nonetheless remains at risk of an early winter.

That reality is what fueled Rizzo's return.

"You get the questions of wait, wait, wait a couple more days," Rizzo said. "But we don't have a couple more days. We've got to win now. I love this team. That's what I want to do. I want to play."