CINCINNATI -- Tanner Roark won the final spot in Washington's rotation during spring training. Halfway through the season, he's the Nationals' top winner.
Roark allowed only three singles over seven innings on Friday night, and Denard Span matched Cincinnati's hit total with his four singles, leading the Nationals to a 4-1 victory that extended their surge and the Reds' slump.
The Nationals won for the seventh time in nine games. They are 56-44, the second-best mark after 100 games in franchise history. The 2012 club went 60-40 on its way to the NL East title.
Roark (10-6) became Washington's first 10-game winner and improved to 3-0 in his last three starts. The right-hander has allowed three runs over 21 innings during those three wins, lowering his ERA to 2.82 -- the best in the rotation.
Nobody would have predicted that during spring training.
"It's pretty cool just to think about," Roark said. "You dream ever since you're a kid of getting to the big leagues. I took the opportunity and tried to run away with it.
"It is a little surprising. It's been a good ride so far. Keep it going."
Rafael Soriano gave up a walk and a double in the ninth while getting his 24th save in 27 chances and finishing the combined four-hitter.
The Reds remain stalled since the All-Star break, dropping all seven games for their longest losing streak in five years. It's the first time they have lost their first seven games after the All-Star break since 1991, when they dropped eight in a row.
Span had four singles, stole a base and drove in a run off Alfredo Simon (12-5), who has lost both starts since his first All-Star selection. The Nationals piled up nine hits, two walks and three runs off Simon in only 4 1/3 innings.
Span is 9 for 18 on Washington's road trip with two four-hit games.
"He's been great," manager Matt Williams said. "The key for him is hitting the ball back through the middle. We've seen that over the last week or so, hitting the ball up the middle or the other way."
Heading into the All-Star break, the Reds won seven of nine at home, cutting their deficit in the NL Central from seven games to 1 1-2. Their worst road trip in five years wiped out most of their gains, but they had hoped to get their offense back in form at hitter-friendly Great American Ball Park.
During the seven-game losing streak, Cincinnati has batted .176 as a team while scoring a total of 13 runs.
"It's just really a mental game," manager Bryan Price said. "When we were going good before the break, nobody was pressing. Now, everybody's pressing. We can't get our offense going because we're not getting a lot of baserunners."
Washington had at least one hit in each of the first six innings, with four players having multi-hit games. The Nationals put five hits together in the fourth for three runs, including Zach Walters' RBI double, Span's single and Anthony Rendon's run-scoring single. Adam LaRoche singled home a run in the sixth off J.J. Hoover.
Walters was called up Wednesday to fill in while Ryan Zimmerman is disabled by a pulled hamstring.
LHP Gio Gonzalez (6-5) starts Saturday for the Nationals. He's 2-0 with a 1.00 ERA in four career starts against Cincinnati. Johnny Cueto (10-6) had his worst start of the season in Washington on May 20, giving up eight runs in only 5 1/3 innings of a 9-4 loss. ... Nationals RF Jayson Werth was back after missing the last game with a sore right knee. ... Reds SS Zack Cozart was hitless, extending his slump to 0 for 17. ... 1B Joey Votto continues to do rehab for the strained muscles above his left knee. He's been on the DL since July 8. "I think we need to let a few more weeks go by before we can really start to see that there's a point in time when we know he's going to be back," Price said.