A sell-out crowd of 42,295 turned out in the nation's capital.
MLB Commissioner Rob Manfred was on hand to throw out the first pitch (he got an assist on the throw) and officially name Nationals Park as the site of the 2018 MLB All-Star Game.
Blockbuster free agent signing Max Scherzer was "as advertised" as Matt Williams told reporters after the loss.
Two errors marred Scherzer's outing and led to the three unearned runs he allowed scoring, and the Nationals failed to do much offensively against either Mets' starter Bartolo Colon or the NY bullpen, but other than that, it was a big day for baseball in Washington.
"All of the people that come watch us play are excited about our season as we are," Williams said in his post game press conference.
"Didn't get off on the right foot, but as you've heard me say, and as we live by, we've got another one in a couple of days. This one is behind us now. We'll see if we can get [Jacob] deGrom and the Mets on Wednesday and go from there."
As for the offense coming up empty against New York's 41-year-old veteran? Williams, as he did often last season, stressed that he believes if the Nats can generate opportunities, they'll score their share of runs.
"We just want to keep providing ourselves these opportunities," he said. "We'll come through, but keep providing those for us and we'll take our chances."
Williams, while acknowledging that Opening Day is different than other games, wasn't willing to blame all the pomp and circumstance for the Nationals' issues.
"Baseball players are creatures of habit," he explained "So, they like to get into the routine. Opening Day is a different routine. But to be part of it is a pretty special deal regardless of where you are and where you're playing. The more Opening Days you're a part of means the better player you are and the more opportunities you have. So if you look at it that way, then it's a great day. We would have liked to have won this one, but we didn't and we move on."
The one offensive highlight came from now-22-year-old, 2010 no.1 overall pick Bryce Harper, who hammered a 1-0 heater from Colon, launching a solo shot to right field in the fourth to put the Nationals up 1-0.
After coming up big in the NLDS, going 5 for 17 with a double and three home runs in four games against the San Francisco Giants, Harper picked up where he left off last season, going 2 for 3 (with two of the Nats' three hits) in the season opener.
The home run off Colon was Harper's third Opening Day home run in three season-openers thus far in his career.
Williams said he saw it as a sign that the Nats' right fielder and three-hole hitter put in the work this winter and is ready for a big 2015. It's also clear, he explained, that Harper likes a big stage.
"I think that he's excited about playing every day regardless of what day it is," Williams said. "But especially Opening Day.
"He worked hard all Spring. He's prepared. I think as we spoke about in the Spring, he's taking those steps necessary to become what he wants to be. And he wants to be a really good player and today he showed what he can do."
Can Harper stay healthy all season and show what he can do in a full campaign after back-to-back seasons in which he's struggled with an injury to his knee (2013) and a torn UCL in his left thumb (2014)?
Harper and the Nationals will have a chance to even things up in the opening series of 2015 tonight when they take on deGrom and the Mets in the second game of the three-game set.
The 2011 National League Rookie of the Year was of 0 for 3 with a K against the 2014 NL ROY last season. Harper gets another shot at deGrom and the Mets tonight.