Werth's homer off Drew Storen helped the Phillies maintain their three-game lead in the NL East over the Atlanta Braves. The teams begin a three-game series in Philadelphia on Monday night with Cole Hamels facing Jair Jurrjens in the opener.
Storen, who has blown two of six save opportunities, entered the ninth with a three-run lead. He gave up a leadoff single to Placido Polanco and a double to Chase Utley. Howard followed with his hit to make it 6-5.
Werth, who had three hits, three RBIs and two runs scored, hit a full-count fastball over the 409-foot sign in center field for the second game-winning homer of his career. It is the fifth walk- off home run for the Phillies this year.
Down 3-1, the Nationals rallied against Phillies starter Joe Blanton for three runs in the sixth. Ian Desmond led off the inning with a single to right field. After a lineout to left, Desmond stole second and Adam Dunn walked. Roger Bernadina popped out to shortstop and Desmond, who was attempting to steal third, had to scamper back to second.
Morse fell behind 1-2 but fought back to a full count before he hit Blanton's cutter into the right-center stands for his 11th home run of the season.
Until the homer, Blanton had been very effective. He struck out eight in six innings and had allowed just a solo shot to Willie Harris in the third.
Trailing 1-0 in the fourth, Werth led off with single against Maya. Raul Ibanez followed with a single and Brian Schneider hit a two-run double to right-center.
Polanco was hit by a pitch to start the fifth. After two outs and a steal, Werth singled him home for a 3-1 lead.
NOTES: Washington OF Nyjer Morgan invited the fan he was accused of hitting with a ball in August at Citizens Bank Park to the game, according to the Nationals public relation staff. Morgan gave the fan a free ticket behind the Nationals' dugout on Sunday. The two met before the game on the field and Morgan also brought him into the clubhouse to meet his teammates and coaching staff. .... With an announced sell-out crowd of 44,936 the Phillies extended their streak of consecutive sellout at Citizens Bank Park to 117. . . Phillies centerfielder Shane Victorino, who was ejected in the sixth by third base umpire Angel Hernandez, went 0-for-4 and had an 11-game hitting streak come to en end.