WASHINGTON -- Eduardo Nunez went 4-for-5 with two triples and a double and scored three times and Brandon Belt had three hits and drove in two runs as the San Francisco Giants beat Stephen Strasburg and the Washington Nationals 7-1 on Saturday to even the three-game series between first-place clubs.

Nunez, acquired in a trade with the Minnesota Twins on July 28, entered the game hitless in his previous 16 at-bats. He tripled and scored in the fourth and fifth and tied a career high for hits in a game.

Giants starter Matt Cain (4-6) went five innings plus one batter and gave up zero runs on five hits with three walks and four strikeouts. It was the first road win of the year for Cain, who lowered his ERA to 5.16.

Stephen Strasburg (15-2, 2.80 ERA) lost for the second time in his last four starts after allowing four runs and eight hits while striking out eight in 4 2/3 innings -- his shortest outing of the season.

Buster Posey had a sacrifice fly in the seventh off reliever Blake Treinen as the Giants took a 5-0 lead. Ehire Adrianza had a pinch-hit single in the eighth to drive in Hunter Pence to make it 6-0.

Washington's Danny Espinosa had his second hit, an RBI single, to trim the margin to 6-1 in the eighth off reliever Jake Peavy. But Derek Law came on to retire Ben Revere on a fly ball with two runners aboard to end the threat.

Belt hit a solo homer off former closer Jonathan Papelbon in the ninth to make it 7-1. Posey (two RBIs) and Brandon Crawford (one RBI) each had two hits for the Giants.

Wilson Ramos had three hits for the Nationals.

The Giants (63-47) had lost 14 of their last 19 but remained two games ahead of the Los Angeles Dodgers in the National League West. Washington (65-45) started the day seven games ahead of the Miami Marlins in the NL East.

Strasburg had a long trip around the bases in the third. He led off with a double and advanced to third on a double play grounder but was stranded when Bryce Harper struck out for the second time.

When Strasburg took the mound in the fourth he gave up a triple to Nunez that hit the top of the wall in center. Posey then had a one-out single to drive in Nunez and make it 1-0. The Giants assumed a 2-0 edge when Strasburg walked Joe Panik with the bases loaded.

The Giants made it 3-0 in the third as Nunez tripled for the second inning in a row and scored on a bloop double to left by Belt. Crawford had a sacrifice fly to build the margin to 4-0.

Strasburg had given up a double with one out in the first to Nunez. The Giants came close to taking the lead but Washington center fielder Ben Revere made a fine running catch on the warning track to rob Posey of extra bases for the third out in the first.

Washington's Trea Turner led off the last of the first with an infield single as second baseman Panik couldn't make the play on a two-bouncer.

Turner appeared to steal second but the call was overturned after a challenge by the Giants. It was the first time Turner was caught stealing in 11 tries in the majors over the past two seasons.

The Nationals left the bases loaded in the fourth as Strasburg fanned for the final out.

NOTES: OF Brian Goodwin entered the game in the top of the seventh for Bryce Harper, who struck out all three times. It was the MLB debut for Goodwin, who flied deep to right in his only at-bat. Goodwin was drafted by the Nationals in 2011 out of Miami Dade Community College. He was hitting .282 with 11 homers and 14 steals in 109 games with Triple-A Syracuse. ... Giants RF Hunter Pence fouled a ball that hit the dirt and came up and hit him in the face in the second inning. He was checked by an athletic trainer and stayed in the game and struck out on the next pitch. ... Nationals LF Jayson Werth had a walk in the fifth to reach base for the 37th game in a row, the longest streak in the majors this year. ... The Nationals placed 1B Ryan Zimmerman on the 15-day disabled list Saturday, retroactive to Aug. 1, and called up OF Brian Goodwin from Triple-A Syracuse. Zimmerman is hitting .222 with 12 homers in 80 games. ... Giants LHP Madison Bumgarner (10-6, 2.25 ERA) faces Nationals RHP Tanner Roark (11-6, 3.02) in the series finale Sunday. ... Giants 1B Brandon Belt, after an off day Friday, was back in the starting lineup and hitting third Saturday. ... Giants veteran LHP Javier Lopez went to Robinson High in nearby Fairfax, Va., and the University of Virginia. He is the only active player who has been part of four World Series titles. ... Washington manager Dusty Baker was the skipper of the Giants from 1993-2002. ... The Giants were 5-for-14 with runners in scoring position after going 10-for-71 in such situations over their last eight games.