Updated

Washington, DC (SportsNetwork.com) - Tanner Roark tossed his first career shutout, as Washington recorded a 4-0 victory over San Diego in the third test of this four-game series.

Roark (2-0) carried a perfect game into the sixth inning, and finished his outing allowing three hits and one walk while striking out eight. Roark has thrown 18 consecutive scoreless innings and in 35 career innings at Nationals Park, he has allowed one earned run.

"I feel confident on the mound. I feel strong. Getting ahead of hitters is biggest thing. Strike 1 is the best pitch you can throw," Roark said.

Ian Desmond came up with three hits and an RBI for the Nationals, who have won two in a row after dropping the opener and three of four overall. Denard Span, Adam LaRoche and Danny Espinosa also knocked in a run each.

Andrew Cashner (2-3) was charged in defeat with nine hits and four runs despite fanning five over six full frames for the Padres, losers in five of their last seven.

Washington picked up three runs in the first inning and gave Roark more than enough room to operate. With two on and one out, LaRoche hit an RBI single, Desmond knocked in a run with a double, and Espinosa plated another on a fly to center.

Roark retired 16 in a row to start the contest, but had his perfect-game bid broken up on Rene Rivera's one-out single in the sixth. Cashner managed to reach on LaRoche's error, but Everth Cabrera fouled out and Chris Denorfia flied out to end the threat.

San Diego had a runner on in each of the final three innings, but Roark only permitted Denorfia, who reached on a one-out single in the ninth, to advance beyond first base.

The Nats pushed across their final run in the home sixth, as Kevin Frandsen reached with a leadoff single, was sacrificed to second and scored on Span's base hit.

"Cash kept us in the game. He always does. He's our ace," Padres first baseman Yonder Alonso said. "Today, we just weren't behind him, we didn't play good defense. It was somewhat of an embarrassment. But this is baseball. We've got tomorrow. We have to learn, 100 percent, from this."

Game Notes

Prior to Saturday, Roark had gone 8-1 with a 2.21 ERA and started nine of his 18 career appearances, never working past the seventh inning in any outing ... The 27-year-old threw 105 pitches, 73 for strikes ... Washington scratched outfielder Bryce Harper, who injured his left thumb sliding into third base during Friday's 11-1 victory. X-rays taken were negative.