WASHINGTON -- Lucas Giolito threw four scoreless innings in his rain-shortened major league debut, and the Washington Nationals beat the New York Mets 5-0 on Tuesday night.

Baseball's top pitching prospect allowed just one hit -- a leadoff single -- struck out one and walked two before a lengthy rain delay ended his outing. The 21-year-old Giolito threw 29 of his 45 pitches for strikes and was in command against the Mets like a seasoned veteran.

Bryce Harper hit a two-run home run, his team-leading 16th of the season, Wilson Ramos drove in two and Anthony Rendon had an RBI triple to provide the run support.

More from FoxSports

Mets right-hander Matt Harvey (4-10) was the hard-luck loser despite striking out three and allowing just four hits in 3 2/3 innings.

Giolito's much-anticipated debut had to wait a little longer after rain delayed the start of the game by 55 minutes. Giolito was handed the ball by Secretary of the Army Eric Fanning and was brilliant after allowing a leadoff single to Curtis Granderson.

Lucas Giolito has used 32 pitches to work through three scoreless innings. #Nats 1, Mets 0 pic.twitter.com/29ShAZG3Av

— #VoteNats (@Nationals) June 29, 2016

The 6-foot-6 Giolito registered his first career strikeout when he got Asdrubal Cabrera swinging and benefited from some nifty defense to get out of the first inning. He cruised until the rain came, and the 85-minute delay made for an easy hook by manager Dusty Baker.

Giolito will have to wait for his first major league victory because he only went four innings. Oliver Perez (2-1) got the win in relief.

Harvey got into trouble in the second inning but was better than he has been for most of the season. He continued his dominance against Harper, who's now 1 for 26 in his career against Harvey.

TRAINER'S ROOM

Mets: Granderson was removed from the game after the second rain delay and replaced by Alejandro De Aza. ... RHP Hansel Robles was struck in the right leg with a line drive in the seventh inning and walked off under his own power. ... LHP Steven Matz has a bone spur in his elbow and had his start pushed back from Wednesday to Thursday. ... RHP Noah Syndergaard has a small bone spur in his elbow but isn't expected to miss any time. ... 1B Lucas Duda is two weeks away from resuming baseball activities.

The #Nats bullpen approves of Bryce's 16th HR of the season. https://t.co/4puyxFqNE7 pic.twitter.com/4N4dw4WH5d

— #VoteNats (@Nationals) June 29, 2016

Nationals: An MRI confirmed RHP Stephen Strasburg has an upper back strain. Strasburg threw a bullpen session Tuesday afternoon.

UP NEXT

Mets: RHP Logan Verrett (3-4, 4.14 ERA) makes a spot start for Matz as the rest of the rotation gets pushed back. The Mets will have one fewer arm available in the bullpen as a result.

Nationals: RHP Max Scherzer (8-5, 3.52 ERA) makes his 17th start of the season trying to bounce back from allowing four earned runs in a loss to Milwaukee on Saturday.