Updated

Cincinnati, OH (SportsNetwork.com) - A solid pitching performance by Tanner Roark, coupled with stellar defense from Anthony Rendon and a barrage of hits from the Washington offense, helped the Nationals defeat the Cincinnati Reds, 4-1, in the opener of the three-game set.

Roark (10-6) limited the Reds to just one run on three hits with six strikeouts over seven innings in his third straight win. Throughout those three wins, Roark has allowed one run over seven innings in each of outing.

"Really efficient. Really efficient with his pitch count from the first batter," Nationals manager Matt Williams said of Roark. "He's got the ability to throw any pitch at any count for a strike. That's the art of pitching. He gives us a chance every time he goes out."

Rendon, who made a couple of dazzling plays filling in for injured third baseman Ryan Zimmerman, went 2-for-4 with an RBI. Denard Span went 4-for-5 with an RBI, while Adam LaRoche and Zach Walters also knocked in a run apiece for Washington, which pounded out 12 hits to win for the fifth time in its last six games.

Alfredo Simon (12-5) was denied his major league-leading 13th win after he surrendered three runs on nine hits and two walks in 4 1/3 innings of work.

While the Nationals' offense was clicking, Cincinnati's managed only four hits in its seventh straight loss.

The last time the Reds lost at least seven in a row was during an eight-game slide from July 28-Aug. 4, 2009.

"We're not at all playing our game right now," Reds manager Bryan Price said. "There is no rhyme or reason. We're just not playing our game."

Bryce Harper and Wilson Ramos each singled to right with no outs in the fourth. Walters then doubled to right that plated Harper for the first run. Following a strikeout of Roark, Span sent an RBI single to right, but was caught in a rundown and tagged for the second out. Rendon picked Span up, though, poking a single out to left for a 3-0 lead.

Roark retired the first nine batters he faced before Billy Hamilton blooped an opposite-field single to left to begin the home fourth. Hamilton stole second with one out and moved to third on Todd Frazier's groundout. Ryan Ludwick then fisted a slow roller off the glove of Roark and hustled out an infield single as Hamilton crossed home to cut the deficit to 3-1.

The Nationals added some cushion in the sixth with a two-out, RBI base hit from LaRoche that pushed the lead to 4-1.

With two outs and a pair of runners on in the bottom of the seventh, Roark worked through trouble with a little help from Rendon, who made a diving stab on Zack Cozart's grounder, then flipped it over to second to end the inning.

Rendon made another sensational play an inning later, bare-handing a bunted grounder up the third-base line and getting the speedy Hamilton at first.

Rafael Soriano wrapped everything up with a scoreless ninth to secure the win and his 24th save of the season.

Game Notes

It was the second straight four-hit game for Span, who joined Dmitri Young (2007) and Brad Wilkerson (2005) as the only Nationals to ever achieve such a feat. ... Cincinnati last tasted victory on July 13, the last day before the All-Star break, in a 6-3 win over the Pittsburgh Pirates. ... Hamilton has 41 stolen bases. ... Washington went 4-for-14 with runners in scoring position and left 12 men on base, while Cincinnati went 1-for-4 in those instances and left six on base. ... The Reds will look to end their losing streak with ace Johnny Cueto taking the hill on Saturday, opposing Washington's Gio Gonzalez.