Not only did Matt Cain bring an abrupt end to San Francisco's shutout streak last time out, but he also failed to extend his own unbeaten run.

The All-Star right-hander aims to bounce back this evening as the Giants try to avoid their first three-game sweep at the hands of the Washington Nationals in six years.

Cain had won eight straight starts before getting a touch-luck no-decision in Oakland on June 24. However, he suffered his first loss since May 1 five days later when the Reds tagged him for five runs on 11 hits and a walk.

The Giants came into the game having recorded four straight shutouts for a 36- inning scoreless streak, but that came to an end when Cain yielded a leadoff homer as part of a three-run first.

"They're an aggressive team and you want to keep them off balance," Cain said on the Giants' website. "I was getting them swinging but wasn't making quality pitches."

The 27-year-old hopes it was just a bump in the road in what has been an excellent season, one in which Cain has thrown a perfect game while going 9-3 with a 2.53 earned run average through 16 starts.

Cain has faced the Nationals 11 times prior, going 5-4 with a 3.09 ERA.

Washington starter Ross Detwiler, meanwhile, faces San Francisco for only the second time in his career this evening. He last faced them during a doubleheader on June 4, 2009 and was charged with a loss for giving up four runs and 10 hits in 5 2/3 frames.

The 26-year-old southpaw looked headed for a solid outing on Friday in Atlanta, throwing six scoreless innings before yielding four runs while recording two outs in the seventh. That left Detwiler with a no-decision in his team's 5-4 victory.

In 17 games this season, 11 of those starts, Detwiler is 4-3 with a 3.30 ERA.

The Nats have taken the first two games of this series to extend their overall winning streak to three in a row. They won for the sixth time in eight contests with yesterday's 9-4 victory, celebrating the holiday by launching four homers.

Ryan Zimmerman, Rick Ankiel, Michael Morse and Jhonatan Solano all went deep as Washington extended its lead for first place in the National League East to 4 1/2 games over the New York Mets.

"It's hard to shuffle the lineup around and have guys hit in different spots all year," Zimmerman said. "Now that we're trying to get healthy, guys are able to find out what they can do and finally get comfortable."

Ian Desmond drove in a pair of runs and Edwin Jackson allowed five hits and four runs over 5 2/3 innings for the win.

The Giants will try avoid getting swept in three games by the Nationals for the first time since July 25-27, 2006 in Washington. They jumped out to a 3-0 advantage in the first inning on Wednesday, but starter Madison Bumgarner was rocked for seven runs over five-plus frames.

"We did what we wanted, put up a crooked number early on," said Giants manager Bruce Bochy. "But you could tell, he was toughing it out in the heat, and eventually it got to him."

Pablo Sandoval finished 3-for-4 and knocked in three runs -- two of those on a homer during the first inning -- for the Giants, losers in four of their last five. That slump has dropped them a half-game behind the Dodgers for the lead in the NL West.

The Nationals won three of four over the Giants at home last season.