WASHINGTON — Austin Kearns’ sacrifice fly with the bases loaded off San Francisco closer Armando Benitez capped a two-run rally in the ninth inning, lifting Washington past the Giants 4-3 on Wednesday night, the Nationals’ fifth consecutive victory.

Benitez (4-2) came on to start the ninth with a 3-2 lead. But the right-hander walked leadoff batter Robert Fick, and, after striking out Alfonso Soriano, he gave up an infield single to Felipe Lopez. Ryan Zimmerman’s RBI single tied the game, and Benitez then walked Nick Johnson to fill the bases.

That brought up Kearns, who’s been adjusting to life with his new team since this month’s eight-player trade that brought him to Washington from Cincinnati.

It was Benitez’s sixth blown save this season, in 19 chances. The Giants were 40-4 when leading after eight innings this season.

The comeback gave Saul Rivera (1-0) his first major league victory. He was Washington’s fourth reliever, and threw a perfect ninth.

Randy Winn’s two-run single in the seventh inning had put San Francisco ahead, despite another quiet night for Barry Bonds.

Bonds went 0-for-2 with two walks, a strikeout and a groundout, making him 0-for-6 in the series. He’s 2-for-12 without a home run over his last five games, leaving him stuck on 722 homers, 33 behind career leader Hank Aaron.

Bonds wasn’t booed quite as much as during Tuesday night’s series opener, but he still heard jeers, including after a running catch in left of Ryan Church’s sinking liner in the fourth.

Giants starter Noah Lowry gave up two unearned runs and eight hits over six innings.

Washington starter Pedro Astacio was charged with three runs — two earned — and six hits. The right-hander took a 2-1 lead into the seventh, but Todd Greene reached on second baseman Marlon Anderson’s fielding error, and Todd Linden — pinch hitting for Lowry — doubled to right. Reliever Mike Stanton came on, and gave up Winn’s hit.

Washington’s first two runs came in the third.

Soriano — at the center of speculation as Monday’s trade deadline nears — legged out a double, beating center fielder Steve Finley’s throw. He moved to third when Lowry had him picked off but second baseman Ray Durham’s throw hit Soriano in the back for an error.