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WASHINGTON -- A smile crept across Adam LaRoche's face when he rounded the bases after his career-best 33rd homer gave him an even 100 RBIs.

After a high-five from manager Davey Johnson and a hug from Jayson Werth, LaRoche acknowledged the crowd's ovation with a tip of his red batting helmet during Washington's 4-2 victory over the Philadelphia Phillies on Tuesday night, 24 hours after the Nationals clinched the NL East title.

"Feels good," LaRoche said, "to have a little celebration two nights in a row."

This one was more muted, of course, than all the alcohol-spraying and mirth-making of Monday. Asked how he'll mark his individual achievement, LaRoche replied: "I don't know. I'm still recovering from last night. I'll have to take it easy tonight."

As he spoke, the televisions in the Nationals Park home clubhouse were tuned to the game between the Yankees and Red Sox -- not Cincinnati's 3-1 victory over the Cardinals, which was relevant to Washington's postseason plans. The Nationals and Reds are tied for the best record in the majors (97-64) heading into Wednesday's regular-season finales, with the top seed in the NL playoffs on the line, something the Nationals insist they aren't all that worried about.

Washington can clinch home-field advantage throughout the postseason with a victory in Game 162 or a loss by the Reds.

"I don't know how it's that important," Johnson said. "You've got to beat the teams you play."

On an evening when a thick fog was hanging over the stadium, Johnson decided most of his main guys deserved a rest. Indeed, LaRoche was Washington's only everyday player who stayed in for more than five innings -- and he led off the sixth by driving the second pitch thrown by reliever Josh Lindblom (3-5) into the home bullpen in right field. Several Nationals relievers raised their fists as the ball cleared the wall.

Last season was rough as could be for LaRoche. Trying to play despite a torn labrum in his left shoulder, he hit .172 with three homers in 43 games, then finally agreed to have surgery.

What a turnaround: In 2012, LaRoche tied his career-best RBI total and joined Ryan Zimmerman and Adam Dunn -- who each did it twice -- as the only Nationals players to reach 100 in that category. He heard some "MVP!" chants from fans in the seventh inning.

"It's unfortunate he got hurt last year, for really the first time in his career. But he's a terrific player and a terrific teammate, and I'm so happy for him," general manager Mike Rizzo said. "Now we're looking for him to get hot and carry us like he did quite often in the first half."

Zach Duke (1-0) threw a scoreless sixth to get his first major league win since Aug. 14, 2011, for Arizona. Drew Storen earned his fourth save in five chances.

Phillies rookie Darin Ruf hit a pair of solo homers -- off Tom Gorzelanny in the fourth inning, and Tyler Clippard in the eighth. All three of Ruf's homers in the majors have come against Washington.

Ruf led all minor leaguers with 38 home runs this year, earning the nickname "Babe."

"I was just trying to put myself in a spot where I can compete next year in spring training for, if not for a starting job, just a spot on the team," said Ruf, who has driven in all seven of Philadelphia's runs over its past three games against Washington.

Johnson used Gorzelanny to begin the game instead of originally scheduled starter Gio Gonzalez, preferring to let the left-hander who is 21-8 with a 2.89 ERA stay fresh for a start in Game 1 of the division series.

LaRoche and center fielder Bryce Harper were the only regulars in Johnson's starting lineup. He opted to sit third baseman Zimmerman, right fielder Werth, left fielder Michael Morse, shortstop Ian Desmond, second baseman Danny Espinosa and catcher Kurt Suzuki.

Instead, the lineup included players such as Mark DeRosa, making his first start at shortstop since 2006 for Texas.

"How about that Goon Squad?" a grinning Johnson said, referring to the nickname Washington's bench players have been given. "Told you they were tough."

Game notes

DeRosa was charged with a fielding error in the third. ... Harper, the NL rookie of the month for September, went 1 for 3 with a single and a stolen base, his 18th, in the fifth inning. Phillies manager Charlie Manuel came out to argue that Harper advanced on a ball fouled off by the batter. ... The third-place Phillies are 81-80. ... Johnson said RHP Jordan Zimmermann will start Game 2 in the playoffs. RHP Edwin Jackson (9-11), pitching the regular-season finale against Philadelphia on Wednesday, or LHP Ross Detwiler (10-8) will take Game 3, depending on the opponent. ... LHP Cliff Lee (6-8) starts for the Phillies on Wednesday. ... LaRoche hit 32 homers for Atlanta in 2006, and drove in 100 runs for Arizona in 2010.