WASHINGTON >> The Washington Nationals announced a paid attendance of 19,195 on Friday night at Nationals Park. It’s unclear how many of those in attendance were Giants fans, but there were more than enough — especially behind the third-base dugout — to start “Let’s go Giants” chants in the lower bowl.

Landen Roupp pitched six-plus shutout innings, and the Giants’ offense jumped on the Nationals’ bullpen once starter MacKenzie Gore left with an injury in the seventh inning as San Francisco beat Washington 4-0 to start a nine-game road trip.

“(Gore’s) pitching a game, Roupp’s pitching a great game, and somebody’s going to blink first,” said manager Bob Melvin. “With (Gore) coming out of the game, we did a good job (against) their bullpen in the end.

“It’s kind of what we do — we jump on bullpens. I would never want somebody going out with an injury, but we did better work after he left.”

Gore and Roupp traded zeros for the game’s first six innings, but the Giants finally scratched across the night’s first runs in the seventh when Gore unexpectedly departed.

After walking Jung Hoo Lee on five pitches to lead off the seventh, Gore left the game alongside a trainer in the middle of a plate appearance against Matt Chapman due to a charley horse in his left leg. The ailment originated in the top of the second inning when Willy Adames hit a line drive off Gore, who finished his night with nine strikeouts.

Chapman finished the plate appearance by drawing a walk against reliever Jackson Rutledge (charged to Gore), and following Wilmer Flores’ 6-4-3 double play, Willy Adames drove in Lee by sneaking a single up the middle.

San Francisco expanded the lead to 2-0 when Rutledge walked Casey Schmitt, Mike Yastrzemski, and Patrick Bailey in back-to-back-to-back plate appearances, and Bailey scored Adames with his free pass with the bases loaded. The Giants had a chance to pile on, but Nationals reliever Zach Brzykcy entered for Rutledge and got Tyler Fitzgerald to hit into an inning-ending groundout.

Roupp cruised through the first six innings but was pulled in the seventh after allowing a double and a walk to begin the inning. Randy Rodríguez entered for Roupp and immediately put out the fire, striking out Robert Hassell III and getting José Tena to ground into an inning-ending 6-3 double play.

From there, left-hander Erik Miller pitched a scoreless eighth inning, and Camilo Doval finished off the win with a scoreless ninth, his 19th consecutive scoreless outing.

“It really is amazing what he’s done this year,” Melvin said. “Lefties, righties. He’s got the toughest assignment. Typically, he’s coming in with guys on base. After a starter gave us six innings, a couple guys on base, and he gives up nothing.

“I want to say it’s just not surprising, but it’s very difficult to do to come on with guys on base and nobody out like that.”

Added Roupp: “Unbelievable. He looks really good right now. Just happy for him to come out of there and throw strikes and get out of that inning.”

While Roupp couldn’t finish the seventh inning, the outing represented his second consecutive quality start, the first time he’s had back-to-back quality starts as a major leaguer. His outing against the Nationals was especially tough given their lineup was composed entirely of left-handed hitters, two of whom (Keibert Ruiz, Josh Bell) were switch-hitters batting left-handed.

Roupp leaned on his sinker and changeup to combat Washington’s lineup, with those two offerings accounting for 51 of his 76 pitches. The right-hander only generated four whiffs, but he limited the damage and stifled the Nationals’ opportunities with runners in scoring position in the second and fifth.

“I had to have (the sinker) today, and I feel like I did a good job of locating,” Roupp said.

The Giants doubled their lead to 4-0 in the top of the eighth inning when Wilmer Flores drove in Lee with a single, tying the Cubs’ Seiya Suzuki for the most in the National League, and Chapman scored from third on a wild pitch. Following Flores’ RBI single, a group of Giants fans began to make their voices heard in the lower bowl.

Worth noting

The Giants’ game against the Los Angeles Dodgers on June 15 has been selected for ESPN’s Sunday Night Baseball. The game will now be played at 4:10 p.m. PT instead of 1:10 p.m.