San Francisco @ Washington Game Overview

Harrison, 23, steps into the spot usually filled by Justin Verlander, who was placed on the 15-day injured listed this week with right pectoral soreness.

All 31 of Harrison's major league appearances over his first two seasons were starts. This season, Harrison (0-0, 3.38 ERA) has appeared in four games, all in relief.

"It's cool," he said of the starting opportunity. "I'm super excited to go out and compete. I'm ready to do it. I've been waiting, and now it's my time. I'm ready to go."

Harrison made six starts earlier this season in the minors, and Giants manager Bob Melvin told MLB.com that Harrison could give the Giants about 60 pitches Saturday, then continue to build back up in his next turn through the rotation.

He is 0-0 with a 4.22 ERA in two previous starts against Washington.

The Nationals will counter with right-hander Jake Irvin (3-1, 3.88). He picked up a win against the Orioles last Saturday in his most recent outing, giving up two runs on five hits over 6 1/3 innings in the 10-6 game. Irvin was staked to a 6-0 first-inning lead and avoided giving up a home run for the first time in four starts.

"My stuff was good," Irvin, 28, said. "I think [catcher] Keibert [Ruiz] and I had a really good game plan. Keibert called a great game. We just tried to challenge guys."

Irvin is 2-1 with a 4.00 ERA in three career starts against the Giants.

On Friday night, Landen Roupp tossed six scoreless innings for the Giants, who did just enough against Nationals starter MacKenzie Gore in a 4-0 win.

Willy Adames' RBI single broke a 0-0 tie in the seventh. Wilmer Flores added an RBI single in the eighth, and the Giants also got runs via a bases-loaded walk and a wild pitch.

Jung Hoo Lee reached base three times with two hits and a walk and scored twice.

After the first two batters reached against Roupp in the seventh, Randy Rodriguez came on and ended the threat by getting a strikeout and a double-play grounder.

"He's got the toughest assignment typically," Melvin said of Rodriguez. "He's coming in with guys on base and he gives up nothing."

Luis Garcia Jr. had two hits for the Nationals, who saw their five-game winning streak end.

One night after Nationals outfielder Robert Hassell III debuted with a 2-for-5 effort, outfielder Daylen Lile went 1-for-2 in his debut. The 22-year-old was called up Friday after outfielder Jacob Young (left shoulder AC sprain) was put on the 10-day injured list.

Washington got a scare when Gore departed with an apparent injury in the seventh inning. He had taken a comebacker off his left leg early in the game, and the leg stiffened. He said after the game that he does not expect it to be a problem.

On offense, the Nationals were shut out after scoring 37 runs during their winning streak.

"We just got away from our plan," manager Dave Martinez said. "There was a lot more pull-side ground balls. When we stayed on the ball, we hit it well to the other side of the field."

--Field Level Media