WASHINGTON — Possibly playing his final home game in D.C., Alfonso Soriano homered in his first at-bat Thursday, and the Washington Nationals beat the San Francisco Giants 6-5 for their season-high sixth consecutive victory.

Soriano’s 32nd homer was his sixth leadoff shot of the season, tying for the major league lead. He’s at the center of talks as Monday’s trade deadline approaches, and the Nationals now embark on a nine-game road trip.

Also a candidate to leave via trade in the coming days is Livan Hernandez (8-8), the workhorse of the franchise’s rotation since arriving from San Francisco before the 2003 season. The burly right-hander made the first start in Nationals’ history last year and was the leader of a surprising run to first place during the first half of 2005, opening 12-2 and making the NL All-Star team.

If this was his final start for Washington, Hernandez left on a strong note, retiring the last 10 batters he faced. Mixing his trademark curveballs in the low 60s with fastballs that occasionally rose above 84 mph, Hernandez allowed three runs and six hits over seven innings.

Micah Bowie pitched the eighth, and Chad Cordero recorded his 17th save despite giving up a two-run homer to Eliezer Alfonzo in the ninth. It was Alfonzo’s second homer of the game and ninth of the season, but Cordero struck out Todd Greene to end the game and deal San Francisco its fourth loss in a row.

After going all season without a series sweep at home, the Nationals have done it in two straight three-game sets at RFK Stadium, coinciding with their new owners’ finalizing of their $450 million purchase of the club.

Giants starter Matt Cain (7-7) allowed six runs on five hits and five walks over 6 2/3 innings.

Ryan Zimmerman hit a two-run homer in the third after Cain hit Felipe Lopez with a pitch, but the big inning was the seventh, when Washington turned three walks into three runs. Nick Johnson drove in two runs with a single off Jonathan Sanchez, and Austin Kearns delivered an RBI single off Vinnie Chulk

The Giants scored on Alfonzo’s solo homer in the third, and two runs the next inning on Alfonzo’s sacrifice fly and Jose Vizcaino’s RBI single — and that was it.

Barry Bonds was out of San Francisco’s lineup, as he usually is for a day game after a night game. He left Wednesday night’s game in the ninth inning with a mildly strained right hamstring, but manager Felipe Alou called that exit precautionary.

Bonds, 0-for-6 in the first two games of the series against the Nationals, remains on 722 homers, 33 away from tying career leader Hank Aaron.

Troubled by his right knee, which had offseason surgery, Hernandez struggled for much of this season. But he said after his last start that his knee has improved, and he’s 3-0 over his last six starts, despite a 5.88 ERA over that span.

“He’s sharper than he has been, throwing less pitches, getting hitters out with less pitches,” manager Frank Robinson said before the game.

Soriano and Hernandez both have said they’d prefer to stay in Washington, and the converted left fielder spoke before the game about the warm reception he’s received after a rocky start to his Nationals tenure.

“The fans, they have a lot of love for me, after only three or four months,” Soriano said.