WASHINGTON – Ryan Zimmerman and the rest of Washington’s suddenly potent offense gave Cincinnati starter Phil Dumatrait a rude welcome to the major leagues Thursday night, and the Nationals beat the Reds 7-3 to cap a three-game sweep.

Zimmerman had three hits, drove in three runs and, on defense, made a slick backhanded stab while down on a knee to grab Jeff Conine’s high hopper to third base leading off the seventh inning.

Washington has scored fewer runs than any other club in the majors, but Ronnie Belliard doubled twice and scored three runs, and Dmitri Young added two RBI singles to back a strong outing from Mike Bacsik (5-6).

The left-hander allowed homers to Adam Dunn and Alex Gonzalez, plus a single, in a three-run third – but otherwise did not allow a hit in his seven innings of work. Indeed, take out that troublesome third, and Bacsik faced the minimum 18 batters over his other six innings.

The only other batter who reached base against the lefty was Ryan Freel, hit by a pitch in the sixth, then erased when Brandon Phillips grounded into a double play.

Bacsik didn’t walk a batter and struck out six en route to winning his third consecutive decision. He was lifted for a pinch-hitter in the seventh, departing after only 81 pitches, 51 strikes.

Jon Rauch threw a hitless eighth, and Saul Rivera pitched the ninth.

Dumatrait (0-1) left after 82 pitches – and those weren’t enough to get him out of the fourth inning of his big league debut. The 26-year-old left-hander was brought up from Triple-A Louisville before the game to help fill in a shuffled Reds rotation.

His first pitch in the majors was a 93 mph fastball that ticked off the top of catcher David Ross’ glove and headed to the backstop. His second pitch? Dropped in between the shortstop and center fielder for a single by Felipe Lopez.

And Washington kept connecting against Dumatrait, scoring one run in the first – which could have been more, but Lopez was easily thrown out at the plate by center fielder Freel – then two in the third, and three in the fourth.

Dumatrait’s line: 3 1-3 innings, eight hits, six runs, three walks, three strikeouts.

The Nationals entered this series averaging a meager 3.79 runs per game. But they managed to score six runs Tuesday, and seven Wednesday, before Thursday’s output – meaning Washington has scored at least six runs in each of the six games it’s played against Cincinnati this season.

Consider this, too: Cincinnati pitchers have allowed more hits and runs than any other NL team’s staff.

The Reds’ runs came in a burst of three consecutive hits. Dunn turned on a 75 mph pitch and drove it over the wall in right for his 28th homer of the season. After Edwin Encarnacion singled, Gonzalez’s two-run shot to left, his 14th homer, made it 3-0.

Notes: Thursday was the 100th anniversary of Hall of Fame pitcher Walter Johnson’s major league debut, and the Nationals marked the occasion by wearing white caps with a red “W” – the hats worn by the Washington Senators in 1927, Johnson’s last season with the club. His grandson threw out the ceremonial first pitch. The Nationals also unveiled a placard in Johnson’s honor that will hang at the team’s new stadium, set to open in 2008. … Before the game, the Nationals unveiled a display that counts down the number of home games left at RFK Stadium. The number read “26” on Thursday.

AP-ES-08-02-07 2141EDT