The most important, hyped and fascinating season in Nationals history began Monday, led by the $210 million ace brought to Washington to help shepherd this talented team to October. After all the fanfare — the boxing-style player introductions, the fighter jet flyovers, the unveiling of the “Home of the 2018 All-Star Game” sign in left field and 17 straight batters retired — Max Scherzer watched a popup unravel all of it. He was walking toward the dugout when the ball fell in. He stopped, screamed at no one and ran to cover home, a botched play having turned an idyllic debut into dust.

At 4:09 p.m., cellphones snapped photos as Scherzer delivered a 91-mph fastball, a called strike to New York Mets right fielder Curtis Granderson. For the next two hours, Scherzer showed the promise of his tantalizing right arm, giving up no hits over the first 52 /3 innings. So when the Nationals fell to the Mets, 3-1, it was through no fault of their top starter.

“Miscue behind him, that was the difference today,” Manager Matt Williams said. “He was really good. As advertised.”

On a sun-drenched afternoon at Nationals Park, Scherzer was betrayed by his defense. Miscues by Ian Desmond were followed by run-scoring hits in the sixth and seventh innings. Bryce Harper provided his usual opening day flair with a solo home run in the fourth off of 41-year-old Mets starter Bartolo Colon, only seconds after his new walkup song played: Frank Sinatra’s “The Best Is Yet To Come.” It is a fitting choice for a team that has been picked as a World Series favorite but jettisoned from the first round of the playoffs two of the past three seasons.

“If we’re hitting on all cylinders, we’re gonna be a great team,” Harper said. “We’re gonna do well and play this game the right way and win ballgames. But it’s not gonna be easy for us.”

Nationals beat writer Chelsea Janes talks about the three areas of concern for the World Series favorites ahead of the team's season opener against the New York Mets on April 5. (Jayne W. Orenstein/The Washington Post)

To help boost their chances this year, the Nationals spent lavishly on Scherzer in a surprising January move. They kept impending free agents such as Desmond, Jordan Zimmermann and Doug Fister instead of trading them. They made 2015 their best chance to make a run at a title.

“You have to look at this group similar to the way you look at the ’13 and ’14 teams,” said Mark Lerner, one of the Nationals’ principal owners. “We had the talent there to go all the way. Unfortunately, it didn’t happen. I think 2012 was a bit of a surprise for everybody because it happened so fast. This team is special on its own. There’s been a lot of changes, especially getting Max. Maybe having Max will put us over the top. Who knows?”

In Game 1 of 162, Max wasn’t enough. The Nationals will be pushed to win close games this month, with their top three hitters — Denard Span, Anthony Rendon and Jayson Werth — rehabbing injuries. The Nationals managed only three hits against Colon.

After walking Granderson in the first, Scherzer settled into a groove, breezing through the rest of the inning, and then the next four innings, with ease. Mets hitters flailed at Scherzer’s mid-90s fastballs, thrown off by his unusual arm angle. He struck out Lucas Duda on a high and outside 96-mph fastball.

Scherzer “can help this team a lot,” catcher Wilson Ramos said. “The other four guys, I’m 100 percent sure, will talk with him a lot during the season. He can help the other four guys to be aggressive and help each other. That’s very good to have this guy on this team.”

But Scherzer’s streak of 17 retired batters was snapped in the sixth inning. He walked Granderson to lead off the inning on four pitches. Then a defensive misplay put Scherzer in a bind. David Wright popped up a pitch into shallow right field, playable for second baseman Dan Uggla. But Desmond raced over and Uggla backed away from a possible collision.

The ball hit Desmond’s glove and fell in. The two-base error put runners in scoring position. Scherzer then attacked Duda with ferocity, following up 96-mph fastballs with an outside 98-mph fastball. “That was my best fastball of the day,” Scherzer said.

The Washington Nationals enter the 2015 season carrying the burden of preseason favorites. With the addition of Max Scherzer to the starting rotation, they are embracing the role with hopes of making it deeper into the playoffs. (McKenna Ewen/The Washington Post)

Duda caught up to the pitch, flicking it into the gap between center and right. Both Mets scored. The walk, error and single turned a no-hitter into a 2-1 deficit.

“He was pitching great, too,” Desmond said. “That’s the problem. He was pitching awesome. The story line was written. Harper hit the home run. Just botched it.”

Another defensive miscue in the following inning put the Nationals in a bigger hole. Desmond snared a hot-shot groundball from Juan Lagares but bounced the throw into the dirt in front of first baseman Ryan Zimmerman, who couldn’t scoop up the ball. The next batter, Travis d’Arnaud, smacked a triple off the center field wall, just missing center fielder Michael A. Taylor’s outstretched glove, to give the Mets a 3-1 lead.

“I felt like I had a good bead on it,” Taylor said. “I thought I had it so I was pretty disappointed when I didn’t pull it down.”

Scherzer admitted the errors were frustrating. He wears his emotions openly. But after each miscue or hit, he walked straight back to the mound, asking Ramos for the ball quickly, raring to go again.

“I also put myself in that situation,” he said. “I mean, a two-out walk on four pitches.”

Scherzer faced four batters in the eighth inning, leaving the game with two outs after allowing two singles. He fired 97 pitches over 72 /3 strong innings. He allowed three runs, all unearned, four hits and struck out eight. For a brilliant stretch from the first inning to the fifth, he was unhittable. As he walked off the mound at 6:05 p.m. with his head down, the announced crowd of 42,295 gave Scherzer a standing ovation, which he appreciated.

“Anytime you lose a ballgame you can always go back and look at what you could do better,” Scherzer said. “Even though I threw the ball well, there’s still stuff I can improve upon.”