Nationals 4, Phillies 2: Adam LaRoche hit a tiebreaking homer in the sixth inning for his 100th RBI of the campaign as host Washington downed Philadelphia.

Steve Lombardozzi drove in two runs and Roger Bernadina had a run-scoring single as the Nationals won their 97th game to remain tied with the Cincinnati Reds in the competition for the National League’s top seed in the playoffs.

LaRoche hit his 33rd homer of the season to start the sixth and snap a 1-1 tie. The blast off Josh Lindblom (3-5) barely cleared the right-field wall.

Darin Ruf homered in the fourth and eighth innings for Philadelphia’s lone runs. Washington pushed the lead back to two on a sacrifice fly by Lombardozzi in the bottom of the eighth and Drew Storen retired the side in the ninth for his fourth save.

Zach Duke (1-0) pitched a scoreless sixth for the Nationals. Tom Gorzelanny started in place of ace Gio Gonzalez and struck out five and allowed one run and four hits in 3 2/3 innings. Washington clinched the NL East on Monday night and manager Davey Johnson decided to scratch Gonzalez and give him additional rest for the Nationals’ postseason opener.

GAME NOTEBOOK: Phillies SS Jimmy Rollins (calf) missed his second straight game and isn’t expected to play in the season finale. … Nationals OF Bryce Harper was named NL Rookie of the Month for September after batting .330 with seven homers during the month. … Ruf has driven in all four of Philadelphia’s runs in the series.