Washington, DC (Sports Network) - Randy Winn went 2-for-4 with two runs batted in, while Matt Cain tossed 6 1/3 strong innings as the San Francisco Giants edged the Washington Nationals, 3-2, to complete a four-game sweep at Nationals Park.

Cain (3-4) allowed a run on eight hits and struck out six for the Giants, who have won their last seven road games. Brian Wilson recorded the final four outs for his 18th save, tying Chicago's Kerry Wood for most in the National League.

"This was a good game and a great series for us," said Giants manager Bruce Bochy. "We played well. Cain was good today. He did what he needed to do - got us deep into the game. He didn't give in."

Bengie Molina went 2-for-5 with an RBI double, while Ray Durham doubled and scored twice, but no other Giant recorded a hit.

Lastings Milledge scored a pair of runs for the Nationals, losers in eight of their last nine games. Jesus Flores drove in a run, while Cristian Guzman and Dmitri Young collected two hits apiece.

Tyler Clippard (0-1) was called up from Triple-A Columbus before the game and got the start, dropping the decision in his Washington debut after surrendering all three runs and all five hits in 4 1/3 frames, striking out six and walking four.

After giving up a run in the first, Clippard settled down into the fifth, when Durham and Winn combined to break a 1-1 tie. Durham laced a one-out double down the line in right, and Winn plated him with a single to center for a 2-1 lead. Molina followed with a drive to deep left that barely evaded the reach of Wily Mo Pena for an RBI double that chased Clippard in favor of Brian Sanches, who retired the side without incurring further damage.

Felipe Lopez's double off the wall in left-center and Pena's single chased Cain with one out in the seventh, forcing reliever Keiichi Yabu into a first- and-third situation. But. Yabu quickly escaped the jam by getting pinch-hitter Aaron Boone to ground into a 4-6-3 double play.

Tyler Walker came on for the Giants in the eighth, and after retiring the first two batters, he loaded the bases by sandwiching walks to Milledge and Flores around a single by Young before Alex Hinshaw got the call from the bullpen. With Kory Casto at the plate, Molina tried to pick off pinch-runner Willie Harris at second with a snap throw, but the throw hit Harris and went into center, allowing Milledge to score. Hinshaw walked Casto to load the bases again, but Wilson came on in relief and got Lopez to line out to end the inning.

"It's not hitting that wins games," said Nats manager Manny Acta. "It's hitting with runners in scoring position, and we didn't do that."

Wilson ran into trouble in the ninth when pinch-hitter Wil Nieves reached on Jose Castillo's throwing error with one out, but capped off the save two pitches later when Guzman grounded into a 4-6-3 double play.

The Giants immediately tagged Clippard in the top of the first, as Durham drew a one-out walk and came in to score when Winn followed up with a double off the wall in left-center.

Milledge ripped a double off the scoreboard in right-center to start the home fourth, then moved to third when Young grounded out and scored when Flores hit a sacrifice fly to left.

Milledge's double appeared to hit the top of the fence and bounce off a Plexiglas barrier for a home run, but the Nationals never disputed the ruling.