The Giants arrived at the ballpark with two things packed away: their suitcases, in the event of a return trip to Washington, and cases of champagne, in the event of a return trip to the National League Championship Series. Several hours later, as fireworks lit up the sky and AT&T Park roared in appreciation, the Giants were flying high and a familiar celebration erupted up in the clubhouse. October is champagne season in San Francisco.

Through 162 games, April through September, the Nationals were the toast of the National League. But over the course of five days in the fall, they were left stunned. A San Francisco team that had been there before is going back. With a drama-filled 3-2 win here in Game 4, the Giants topped Washington three games to one in the National League Division Series, advancing to the NLCS for the third time in five years. They’ll square off against the St. Louis Cardinals, beginning with Game 1 Saturday in St. Louis.

“I really have a gritty bunch out there,” said Giants Manager Bruce Bochy. “I told them earlier, there’s nobody whose will is stronger than theirs.”

It was never flashy and never overwhelming. But that’s not exactly this team’s style. “There’s not one guy trying to shine brighter than the next,” reliever Sergio Romo said. The Giants seemed to acknowledge before the series they lacked Washington’s star power and talent level. But what they had was experience, which come October means patience. Long before Tuesday night’s first pitch, outfielder Hunter Pence spoke like he’d just consulted his word-a-day calendar. “Experience,” he said, “is kind of an ephemeral thing.” E-phem-er-al, adj., lasting for a very short time.

“There’s a confidence in knowing you’ve done it before, understanding of the emotions and the adrenaline,” he said. “And beyond that, it’s about getting it done on the field.”

D.C. Sports Bog's Dan Steinberg makes and shares with Post staffers a banana and mayonnaise sandwich, which Nationals bullpen coach Matt LeCroy has eaten with successful results before eight of the team's must-win games this year, including Monday night's Game 3 victory over the Giants. (Post Sports Live/The Washington Post)

The Giants, as they had all series long, waited for their spots. They remained steady, threw smart pitches, played sturdy defense and eked out just enough offense. Just as importantly, they took advantage of Washington’s mistakes and pounced when it was time. Sure, Bryce Harper hit a homer that challenged physics (and tied the game) and Nats’ reliever Aaron Barrett threw a pitch in the dirt that defied logic (and lost the game). All the Giants had to do was wait.

“They kept fighting,” Bochy said of his club. “When they tied the game, we put pressure right back on them.”

In the seventh, not long after Harper’s moonshot splashed down in the bay, the Giants loaded the bases. It wasn’t glamorous — it rarely is with this team — but Joe Panik and Buster Posey singled and Pence walked. Then Barrett skipped a fastball near the front of the plate that bounced by catcher Wilson Ramos, allowing Panik to score the go-ahead run. Unspectacular perhaps, but maybe appropriate, too

“That’s our way sometimes,” Bochy said. “We scratch and claw for runs.”

Among Tuesday’s unlikely stars was starting pitcher Ryan Vogelsong, who’d entered the game coming off five straight terrible starts. Bochy was more concerned with his pitcher’s October record, though — in 2012, the Giants won all four of Vogelsong’s starts — and he certainly didn’t disappoint Tuesday night.

“Just a gutty effort,” Bochy said.

Throwing harder than he had all year, Vogelsong was cruising early. He needed only seven pitches to get out of the second and didn’t allow a hit through the first four innings.

“Every time we’re here and I’m getting ready for a game, I think back to when I was a kid playing in the backyard and make-believing I was in this situation,” Vogelsong said. “I just love it.”

“Every day and every time we’re here and I’m getting ready for a game, I think back to a kid playing in the backyard and make-believing that I’m in this situation,” Vogelsong said. “I just love it.”

With Tuesday’s outing — just one run on two hits through 52 / 3 innings — Vogelsong is now 4-0 in the playoffs and has allowed four runs in 301 / 3 innings, a 1.19 ERA. Through four games against the Nats, the San Francisco starters allowed a total of only four runs in 252 / 3 innings.

Defensively, the Giants did all they needed to. In the sixth, when Werth fired a bomb to the opposite field, Pence tracked it to the warning track, snaring the ball near the top of the wall. The veteran crashed into the wall, rattling as he fell to the ground with the ball squeezed tightly in his black glove.

“Nothing surprises me with this team,” Vogelsong said.

The Giants players took their suitcases home late Tuesday night and earned the right to empty those champagne cases in a raucous clubhouse shower. It’s a scene that’s played out before here, one an unpretentious Giants team will try to repeat twice more this month. No, they’re not the most talented team in baseball. But experience has taught them over the years how to pop the cork at the right time.