BALTIMORE (AP) -- Trey Mancini capped a three-homer binge in the first inning against Gio Gonzalez, and the Baltimore Orioles beat the Washington Nationals 6-4 on Monday night for their season-high fifth straight victory.
Kevin Gausman (2-3) limited baseball's most potent offense to two runs over seven innings. He retired the first 10 batters and struck out eight in his longest outing of the year.
Joey Rickard hit a leadoff homer and Mark Trumbo added a solo shot before Mancini connected with a runner on to make it 4-0. That was enough offense for the Orioles, who now hold a 37-24 advantage over their neighboring rivals in the so-called "Beltway Series," which began in 2006.
Caleb Joseph had a career high-tying four hits for the Orioles. Baltimore (21-10) owns the second-best record in the majors behind the AL East-leading New York Yankees.
Bryce Harper homered and drove in two runs for the Nationals, who lead the majors in runs, hits and batting average
After the Orioles let a six-run cushion shrink to three, Brad Brach worked the ninth for his eighth save. After Brach gave up a one-out RBI double to former Oriole Matt Wieters, pinch-runner Trea Turner strayed too far from second base on a groundout to first and the game ended with a rundown in which Adam Lind was tagged out between third and home.
Gonzalez (3-1) came in with a National League-leading 1.64 ERA for the team with the best record in the NL. None of that mattered to Baltimore, which took the lead for good when Rickard sent the left-hander's fourth pitch into the left-field seats.
Gonzalez made it through six innings and gave up six runs -- one fewer than his previous six starts combined. His poor outing upped his ERA to 2.64 and dropped his career record against Baltimore to 1-6.