The Padres spotted Bass a 3-0 lead in the first and he made it stand up. He struck out seven and walked one. Four of the hits he allowed were singles.
The other was a fifth-inning home run by Washington's Bryce Harper, who hit the first home run of the his major league career Monday.
San Diego was already up 5-0 by that time and had chased Nationals starter Stephen Strasburg (3-1) from the game. Strasberg lasted just four innings, giving up seven hits and four runs. He walked two and struck out five.
Will Venable, who had four hits, opened the game with a double off Strasburg. After a strikeout, Chase Headley walked. Yonder Alonso followed with a single that scored Venable. Both runners advanced on an out and a walk loaded the bases before John Baker singled to center and scored Headley and Alonso.
James Darnell hit his second career home run in the third in making the score 3-0 and Baker singled in Orlando Hudson in the fifth. Baker, who had three hits to go with his three RBI, scored on a Venable single in the eighth to finish the scoring.