Gio Gonzalez dominates the Mets for six innings at Citi Field, allowing three hits and one walk on 91 pitches while also helping his own cause by blasting a home run in the fifth inning. (Elsa/Getty Images)

Ceremony ceded Wednesday night to routine. In the previous two days, the Washington Nationals had welcomed a new manager, absorbed the loss of their cleanup-hitting catcher and basked in a dramatic victory for an entire off day.

Opening day is an event unto itself, and baseball is not an event kind of sport. Game 2 brings the first real slice of baseball’s toil, the start of six months packed with sparse breaks, debated decisions, loopy moments and, for the Nationals, 18 chances to take advantage of the New York Mets.

“Season starts today,” Jayson Werth said Wednesday afternoon, standing in the Nationals dugout during batting practice. “Now we can go.”

In the unofficial beginning, Gio Gonzalez’s six dominant innings — and his harebrained home run — lifted the Nationals to a 5-1 victory over the Mets at Citi Field. Manager Matt Williams’s unexpected lineup produced 13 hits, including Ian Desmond’s booming solo home run and Werth’s four knocks. The Nationals thumped new Mets starter Bartolo Colon and won for the 21st time in 25 games in New York.

Gonzalez struck out six and the Nationals’ bullpen punched out seven more Mets in three scoreless innings. The 13 strikeouts pushed the Nationals’ two-game total to 31, which, according to the Elias Sports Bureau, is the most by any team in its first two games since 1900.

“I just think it’s a byproduct of the way they go about it,” Williams said. “We preach pitching to contact because we want quick innings and lower pitch counts and all of those things. But they’ve got good stuff, too.”

First baseman Adam LaRoche, who moved into the cleanup spot in the Nationals’ first game after Wilson Ramos underwent hand surgery, drove in the Nationals’ first run with a double. Bryce Harper, who dropped to sixth in the lineup, did little at the plate but ended the Mets’ last rally when he threw out a runner at the plate.

For the Nationals to take back the National League East, handling the business of beating the Mets will be important. Their upcoming series against the Atlanta Braves will draw more anticipation, but the Nationals can fatten up by treating the Mets like an overmatched foe. For two games, they have.

“I like more about how chemistry [is] in the dugout, stuff like that,” Desmond said. “Seems like a lot of players are focused. I’m more encouraged by what I see inside the dugout than what I do on the field. And obviously what’s on the field is really good, too. So it’s a good sign.”

Gonzalez led them Wednesday night. Juan Lagares led off with a triple and scored on a sacrifice fly. When Gonzalez came into the dugout, Williams told him, “We need you to finish strong.”

The Mets barely touched Gonzalez again. Using 91 pitches over six innings, Gonzalez yielded only three hits and a walk while striking out six. He found a rapport with Ramos’s replacement, Jose Lobaton.

“He has a good touch and feel for me already,” Gonzalez said. “It’s fun throwing to him.”

Gonzalez even helped the Nationals seize control at the plate. Two batters after Desmond’s home run landed 15 rows deep, Colon threw Gonzalez a 90-mph fastball, over the plate’s heart at chest-level. Gonzalez tattooed a homer of his own to left. As Gonzalez ran to first base, improbability yielded to hilarity.

Gonzalez’s drive deflected off a railing over the left field fence. The umpire twirled his hand to signal a home run. Gonzalez never saw him; he only saw the ball trickling back toward the infield and left fielder Andrew Brown giving half-hearted chase. Gonzalez sprinted to second, saw the distance between Brown and the ball and bolted to third, too.

Third base coach Bobby Henley waved Gonzalez home. Arms waving and head bobbing, Gonzalez continued his sprint. He still thought he was trying for an inside-the-park home run.

“The way I was running, I was like ‘I got a chance,’ ” Gonzalez said. “I was about to slide home.”

Mets catcher Travis d’Arnaud spared him when he told Gonzalez to slow down. Gonzalez still cruised about 20 feet past the plate. Gasping for air, he looked up and saw his brother, Max, sitting in the front row behind the backstop. “I was just trying to find an oxygen tank,” Gonzalez said.

Gonzalez accepted high-fives from giggling teammates as he walked back into the dugout.

“All the bullpen guys told me, ‘You were running away like you were running from the cops,’ ”Gonzalez said. “I don’t know what that is about.”

“That was epic,” Desmond said. “That’s going to go down in the memory bank for a long, long time.”

In the rare moments Gonzalez needed help, his defense provided it. With two outs in the fifth inning and Ruben Tejada on first, Lagares smoked a change-up down the third base line. As Tejada sprinted around second, the ball deflected off the part of the fence that jutted out. Harper chased it down.

By the time Harper scooped the ball in shallow left, Tejada had already taken two steps past third base. Wanting to avoid an airmailed throw, Desmond yelled at him, “Keep it down!”

Harper unleashed his right arm. The ball sizzled on a line, no higher than seven feet off the ground. It skipped on the infield grass directly into Lobaton’s mitt. Tejada, perhaps stunned at how quickly the ball had arrived, slowed down rather than sliding into Lobaton, who tagged him out.

“The things that he can do with that arm are pretty special,” Desmond said. “Your instincts tell you what a normal outfielder can do, not someone with a bazooka can.”

For the last four innings, the Nationals piled up strikeouts, tacked on to their lead and gave Williams a reprieve after a harrowing debut. They will show up Thursday morning and try to sweep the Mets, another blip of business, another step in a marathon. Opening day has passed, and the season has started.

“Day 2 is just as important as Day 1, and tomorrow is just as important as today,” Williams said. “What you worry about is a little bit of a letdown. With everything coming out of spring and a day off, it’s easy to have a letdown. But they didn’t. They were ready to go today, which was great.”