Nationals 14, Giants 2: Kurt Suzuki’s three-run double capped a seven-run third inning and visiting Washington routed San Francisco in the opener of the three-game series.

The expected pitchers’ duel between the two division leaders never materialized as the Nationals sent 12 batters to the plate in the third and scored seven runs on seven hits.

Giants starter Ryan Vogelsong (10-6) tied his career high with eight runs allowed over 2 2/3 innings and his National League-best 2.27 ERA climbed to 2.72.

Backed by the early run support, Gio Gonzalez (15-6) gave up two runs over 6 2/3 innings. Washington improved to 10-4 this month and moved 5 1/2 games in front of Atlanta atop the National League East.

The Nationals extended their lead to 10-0 in the fourth when they loaded the bases and Roger Bernadina doubled in two runs before Suzuki singled in his fourth run of the game.

San Francisco, which dropped into a tie for first place in the NL West with the Dodgers, has lost all four matchups against the Nationals this season. The Giants avoided being shut out when Brandon Crawford hit a two-run home run in the seventh.

Danny Espinosa went 4-for-5 with a two-run homer and three RBIs for the Nationals, who scored a season-high 14 runs and outhit the Giants 21-8. Bernadina also had four hits and three RBIs while Steve Lombardozzi, Ryan Zimmerman and Suzuki had three hits apiece.

Vogelsong, whose streak of completing at least six innings ended after 22 starts, had allowed 12 earned runs in his previous 76 innings at AT&T Park this season.

GAME NOTEBOOK: Giants manager Bruce Bochy was ejected for the second time this season in the third inning for arguing a call at first base. …Nationals OF Jayson Werth was scratched from the starting lineup with right ankle soreness and is day-to-day. … The Giants activated 3B Pablo Sandoval from the 15-day disabled list and optioned 1B Brett Pill to Triple-A Fresno. Sandoval didn’t start Monday, but flied out as a pinch hitter in the ninth.