WASHINGTON -- Lindsay Frost, the mother of Lucas Giolito, is a veteran actor who appeared on "Frasier" and other television shows.

Rick Giolito, his father, has extensive Hollywood experience as a video producer.

Both were on hand Tuesday night at Nationals Park as Giolito, 21, a right-handed pitcher who grew up in the shadows of Hollywood, made his major league debut with a start for the Washington Nationals against the rival New York Mets. He allowed one hit and no runs in four innings before departing after a rain delay and left with the Nationals leading 1-0 against Matt Harvey of the Mets.

Washington beat the Mets 5-0, though Giolito did not figure in the decision.

"I thought it would be 72 degrees and sunny," said Giolito, who made 67 appearances (with 65 starts) in the minors, compiling a 24-13 record and a 2.74 ERA. "It ended up being fun. I never saw the forecast at all. I will take what I can get."

Bryce Harper hit a two-run homer in the fifth inning for some insurance runs.

"He pounded the strike zone," Harper said of Giolito. "He kept them off balance. He had a great mentality going out there. He is going to help us. It was really fun to watch."

The top pitching prospect in the minors is mature beyond his years both on and off the field. So does that come from being around Hollywood stars as a young boy?

"I think it is actually from the fact he had a focus (for baseball) at a very young age," said his father while watching the game.

Wilson Ramos, who caught the shutout, had two hits and his two-run double in the seventh gave the Nationals a 5-0 cushion.

The first-place Nationals (46-32) are five games ahead of the Mets (40-36), who have lost seven of their last 11 games.

The winning pitcher was Oliver Perez (2-1), who made his 32nd appearance of the season.

Harvey (4-10) was the hard-luck loser as he allowed one run but did not return after a rain delay in the fourth.

"Best he has felt all year," Mets manager Terry Collins said of Harvey. "Some of the best stuff he has had all year. He was outstanding."

The Mets loaded the bases in the sixth, but Perez retired James Loney and Wilmer Flores for the last two outs to end the rally. Sammy Solis pitched two scoreless innings, the seventh and eighth, for the Nationals and Shawn Kelley came on to pitch the ninth.

Giolito was 5-3 with a 3.17 ERA in 14 starts this season for Double-A Harrisburg of the Eastern League.

The Nationals took a 1-0 lead on a RBI triple in the second by Anthony Rendon. His hit scored the slow-footed Ramos, who singled with one out off Harvey.

Harper went deep off reliever Jerry Blevins, his former teammate, to give the Nationals a 3-0 lead in the fifth. The two-run shot, Harper's 16th homer of the year, landed in the Washington bullpen over the right field fence.

Harvey gave up one run in 3 2/3 innings and, like Giolito, did not return after a rain delay in the bottom of the fourth. That meant the Mets bullpen again was used heavily, but Collins said he does not need extra arms.

"It is frustrating," Collins said of the two delays. "It is part of the game."

Nationals manager Dusty Baker credited the grounds crew for getting the field ready after the delay in the fourth.

"We thought (the game) would start on time. An emotional swing" for Giolito, Baker said.

NOTES: To clear a roster spot for up RHP Lucas Giolito, Washington optioned RHP Rafael Martin to Triple-A Syracuse. The Nationals also released RHP Taylor Jordan, who was with Syracuse after he pitched in 18 games (15 starts) for Washington from 2013 to 2015. ... Mets GM Sandy Alderson announced before the game that LHP Steven Matz (7-3, 3.29 ERA) will not pitch Wednesday in Washington and instead will be pushed back to Thursday in New York against the Chicago Cubs due to a spur in the back of his elbow. There is no structural damage to the elbow, according to Alderson. RHP Logan Verrett (3-4, 4.14) will face Nationals RHP Max Scherzer (8-5, 3.52) on Wednesday. ... Mets OF Juan Lagares (sprained left thumb) went 1-for-4 on Tuesday in his first rehab game for Double-A Binghamton.