Clarke (1-2, 5.26 ERA), who made his major league debut on April 20, grew up about 35 miles from Nationals Park in Ashburn, Va.
The 26-year-old began his college career at Towson University near Baltimore, then decided to transfer when the Tigers came close to dropping the program. Clarke wound up at College of Charleston in the Colonial Athletic Association, and was drafted by Arizona in the third round in 2015.
"There was uncertainty in the program. I thought I would get out when I can. I thought it was the best move for me," Clarke said of leaving Towson.
Clarke had Tommy John surgery in 2013, before leaving for College of Charleston in South Carolina.
"He wound up being really good for us," College of Charleston coach Monte Lee said in a 2013 interview. "He pounds the strike zone. He is one of the best pitchers in the CAA. It's a great story."
Clarke, who has never started against Washington, will make his sixth start of his career on Saturday. He also pitched once out of the bullpen for the Diamondbacks this season.
Clarke will have a tough task Saturday as he faces Washington veteran Stephen Strasburg (7-3, 3.36), who is 5-3 with an identical 3.36 ERA in his career against Arizona in 11 starts.
Strasburg was 1-1 with a 4.15 ERA in two starts last year against Arizona and has faced them in every season since 2012.
But the defense of Gomes has been suspect -- he has seven passed balls, tied for second-most in the majors -- and Martinez decided to go with Suzuki on Friday.
"It has been working well," Washington manager Dave Martinez said of Suzuki and Scherzer.
Clarke follows Robbie Ray in the rotation. The Arizona lefty, who started Friday, was drafted by the Nationals out of high school in Tennessee.
Ray gave up five runs in the 7-3 loss as Washington center fielder Michael A. Taylor had two steals and scored two runs. Scherzer got his fifth win as he fanned 10.
"We are scoring runs for him now. He is pitching the same; he keeps us in every game," Martinez said of Scherzer. "I appreciate him every single day."
"Put another one in the book and come back tomorrow and do the same thing," Taylor told Mid-Atlantic Sports Network (MASN) after the game.
Arizona catcher Carson Kelly hit a homer Friday and 18 of his 34 hits have been for extra bases.
-- Field Level Media