SAN FRANCISCO – Matt Cain pitched a four-hitter, Dave Roberts singled home a run in the eighth inning and the San Francisco Giants earned their first three-game home sweep of the season Thursday with a 1-0 win over the Washington Nationals.

Cain (6-8), the hard-throwing right-hander who’s had his share of hard luck the past two seasons, retired his first 11 batters and didn’t issue a walk for the first time this year. After going 0-2 in his previous three starts, he struck out four in an efficient, 113-pitch performance to boost his strikeout total to 130.