SAN FRANCISCO -- For eight innings, the Chicago Cubs looked like anything but themselves. They certainly did not look like the best team in baseball. All signs pointed to an NLDS Game 5 taking place Thursday back at Wrigley Field against a San Francisco Giants team that would have all the momentum.

Then the ninth inning happened. Make that then the incredible happened.

"We didn't play Cubs baseball for eight innings," Cubs president Theo Epstein said in a champagne-soaked locker room after the game. "We didn't have good at-bats. We weren't playing heads up. We weren't ourselves. That frustration contributed to the eruption in the ninth."

Down 5-2, the Cubs scored four times and won 6-5 to shock a team that had won 10 straight games when facing elimination. It all came crashing down on San Francisco in a manner of minutes, as Cubs veterans started the rally and young players finished it off to send the Giants home for the winter.

"Hitting before the ninth inning is clearly overrated," Epstein said with a smile.

How it happened

Kris Bryant led off with a single, which led to Giants manager Bruce Bochy's first pitching change and the first key at-bat of the ninth inning. Lefty Javy Lopez entered to face lefty Anthony Rizzo, who had shown signs of coming out of his series-long slump after he drew a walk and got a hit earlier in the game. He walked again on six pitches, and in the stands, the Cubs front office watched nervously but with some newfound confidence.

"Once he drew that walk, I thought, ‘Hey, maybe we can do this,'" general manager Jed Hoyer said.

Rizzo's walk was followed by key at-bat No. 2. After Bochy brought in righty Sergio Romo, Ben Zobrist promptly doubled to right field, and the comeback was truly on. The Giants' lead was 5-3 after Bryant crossed the plate.

"After the game, even on the mound, there taking the photographs, the guys were chanting, ‘We don't quit, we don't quit,'" manager Joe Maddon said postgame.

Speaking of Maddon, the wheels in his head started turning at that point. He decided to pinch hit for Addison Russell, who accumulated 95 RBIs during the regular season. It was a gutsy move -- though Russell had been struggling.

"It's hard to take out Addy with all those RBIs, but Romo can be death on righties," Hoyer said.

When Chris Coghlan stepped to the plate to hit for Russell, Bochy made yet another pitching change and brought in lefty Will Smith. Maddon burned Coghlan and asked his rookie catcher, Willson Contreras, to grab a bat. Key moment No. 3 was upon us.

"I saw him [Contreras] working in the cage," reliever Pedro Strop said as Contreras poured champagne on him 20 minutes later. "I saw him focused going into the game."

Contreras knew he had to keep his wits about him. The tying run was on second base.

"After my first swing, I was thinking, slow things down," Contreras said. "I knew I had to calm down. I just wanted to hit a ground ball to the right side."

Instead, Contreras singled up the middle and tied the game as Rizzo and Zobrist crossed the plate. It was 5-5.

"The surprise is how grounded these guys are and how much understanding of the game they have," pitcher Jon Lester chimed in while standing soaked in the middle of the locker room. "That was never the case for me. It takes a long time to learn that. These guys are doing it at 22 years old."

It's a topic that kept coming up as the beer and champagne flowed in the clubhouse after the clinching win: young players performing with the maturity of veterans. The Cubs have a system that is churning out kids ready for the biggest stage of postseason baseball.

"I'm impressed, but it doesn't surprise me," Lester said. "I saw it 10 years ago [in Boston] with Theo. It's one of the reasons I came here."

The Cubs weren't done. The game was still tied when Jason Heyward bunted into a force out that led to him standing on second base after a throw got away. The lead run was now 180 feet away, and at that point, there could be only one person who would come to the plate to put the final nail in the Giants' coffin: Javier Baez.

"If they had an MVP of the division series, you would have to give it to him," Hoyer said. "I'm glad Cubs fans don't take him for granted."

Baez broke his bat while singling the winning run home to cap a highlight-reel series for the 23-year-old infielder. Between his big hits and acrobatic defensive plays, Baez came of age over the four games.

"He was incredible," Strop said. "Javy can do anything. He owned this series. I've never seen anything like it."

Two more great defensive plays combined with the winning hit on the biggest stage to vault Baez into a new standing in baseball. His combination of talent and instincts is lethal, and now the Giants know it. Baez capped a ninth-inning rally that capped an incredible NLDS.

What else do the Cubs have in store for the baseball world as they march toward history? It'll be hard to top Tuesday's 6-5 win. It was a victory for the ages.

"This is the perfect group to do that stuff," Strop said. "The craziest ending I've ever seen."