Cincinnati, OH (Sports Network) - Adam Dunn hit a three-run homer and Edinson Volquez was effective over six innings as the Cincinnati Reds held on to edge the Washington Nationals, 6-5, sweeping a four-game series at Great American Ball Park.

Jerry Hairston Jr. finished with two hits and a pair of RBI and David Ross knocked in another with a double, for the Reds, who have won seven of their last nine games.

Volquez (11-3) earned the win, giving up three runs on five hits, while striking out three and walking three. It was his first career start versus Washington. Volquez on Sunday was selected to play in the 79th All-Star game on July 15th at Yankee Stadium. Francisco Cordero earned his 18th save of the season.

Cristian Guzman drove in two runs, while Felipe Lopez went 2-for-4 with two runs scored for Washington, which has dropped five in a row and seven of its last nine. Guzman will represent the Nationals in the mid-summer classic and now has a 14-game hitting streak.

Collin Balester (1-1) suffered the loss in only his second career start. The right-hander was touched for five runs on four hits. He fanned three and issued three walks.

With the Reds holding a 6-3 lead after eight innings, the Nationals made it interesting off Cordero in the ninth. After the hard-throwing closer retired the first two batters, Lopez singled to keep the game alive. An error by Joey Votto at first base put runners on first and third and an RBI infield single by Guzman made it a 6-4 game. Austin Kearns' base hit to right made it a one-run contest. Cordero, however, got pinch-hitter Wil Nieves looking on a 3-2 slider to end the game.

With the game scoreless after two innings, Washington loaded the bases with nobody out in the third. Roger Bernadina walked to get things going, Balester was hit by a pitch and Lopez walked. Following a mound visit by Reds pitching coach Dick Pole, Volquez gave up a run-scoring single to Ronnie Belliard and a force out plated another to give the Nationals the early 2-0 lead.

Washington kept the offense going as Kearns walked to reload the bases and a free pass to Dmitri Young forced in a run. Paul Lo Duca grounded into a 5-4-3 double play to end the inning.

After the Nats squandered a second and third situation with one down in the top of the fourth, Dunn's three-run homer to right on a 2-2 fastball in the home half, tied the game at 3-3.

David Ross' double down the left field in the fifth scored Votto, who led off the frame with a walk. Volquez then dropped a sacrifice bunt and reached first on Young's error, moving Ross to third. Hairston followed by grounding into a force out that scored a run, putting the Reds up by a 5-3 margin.

With the bases loaded and two down in the sixth, Cincinnati lifted Volquez in favor of pinch-hitter Javier Valentin. Valentin, first-pitching swinging, flied out to shallow right to end the threat.

Cincinnati threatened again in the seventh, putting runners on second and third with two outs, but Charlie Manning struck out Dunn to get out of trouble.

Hairston's looping RBI single to center in the eighth extended the Reds lead to 6-3.