Being an early-April contest, Arroyo was removed after 94 pitches, and the Reds went on to lose the game. But a hot Arroyo gets another crack at the Nats in Sunday's series finale at Great American Ball Park, looking for similar results.
He'll need to pitch well to help the Reds avoid a sweep, which would be the Nationals' first in Cincinnati since the franchise moved to Washington. Edwin Jackson gets the ball for the Nats.
Jackson (1-1, 3.49 ERA) is coming off a start in which he was done in by a fourth-inning homer. He otherwise pitched great, allowing two runs on three hits in seven innings, but was given a no-decision in a game the Nats eventually lost.
For the Reds, third baseman Todd Frazier will likely remain in the lineup in place of the injured Scott Rolen. Manager Dusty Baker is hoping to see the young player cash in on his opportunity.
"Well, it's up to the player," Baker said. "I give guys opportunities, and hopefully he can continue swinging well. ... The opportunity presented itself to him, especially when some of the other guys struggled."
Despite their hot start, the Nationals are still in search of their first sweep of a series of three games or more this season. They can get that with a win Sunday against Arroyo, who is 2-1 this season with a 2.75 ERA.
Nationals: Harper needs stitches, but is OK
Rookie phenom Bryce Harper needed 10 stitches above his left eye Friday night after he swung his bat against a wall following a groundout. The bat ricocheted and gashed Harper's forehead.
Harper, however, said he felt fine. He started in right field, going 0-for-4 on Saturday.
Even with three runs in the opening frame on Friday, the Nationals are last in the Majors in first-inning runs, with just six this season.
Nationals pitchers have surrendered just 15 home runs this year, the fewest in baseball.
Reds: Rolen to DL
Rolen was placed on the 15-day DL with a strained left shoulder on Saturday. Mike Costanzo joined the 25-man roster from Triple-A Louisville to take Rolen's place.
"We're going to address it and take some time off," Rolen said. "[I will] try to do a lot of stretching, try to get a lot more mobility, and try to get the inflammation out of there that is causing the problems."
It's the same shoulder that has needed multiple operations in the past, including surgery last August.
In 29 games this season, Rolen is batting .174 with a .238 on-base percentage.
Should the Nats complete the sweep Sunday, they would equal their 2007 mark against Cincinnati of 6-1, the best ever season series for Washington vs. the Reds.
Four of the last seven games between the Nationals and Reds have gone to extra innings.