DENVER -- Todd Helton was due.
Hitless in his 10 previous plate appearances, Helton connected for a tiebreaking grand slam in the seventh inning Sunday to lead the Colorado Rockies to a 13-9 victory over the Washington Nationals and a sweep of their season series.
"It felt like a long time since I put a good swing on a ball," Helton said.
Matt Holliday homered and drove in three runs to help the Rockies outslug Washington. Helton broke an 8-all tie with his fourth career slam.
"Todd needed it," Colorado manager Clint Hurdle said. "The team needed it on a day when pitchers couldn't find their control and couldn't get people out."
Garrett Atkins also connected and Kaz Matsui added three RBI for the Rockies, who won all eight meetings with Washington this year -- the first time they've swept a season series from an NL opponent in their 14-year history. Plus, Colorado matched its 2006 total of 67 wins.
Holliday finished 3-for-5 with his 28th home run of the year. Jose Mesa (1-5) retired the only batter he faced in the seventh to earn the win.
Alfonso Soriano got four hits and Ryan Zimmerman went 3-for-4 with two RBI for Washington. Nook Logan homered, tripled and had a career-high three RBI.
"What is there to explain about this one?" Nationals manager Frank Robinson said. "You know you're not going to win ballgames when you don't play well defensively and you don't get good pitching."
With the score tied at eight in the seventh, the Rockies loaded the bases against Chris Schroder (0-2). Helton then hit a 2-0 pitch into the Colorado bullpen in right.
"I got all of it," he said. "I can't remember the last time I had a no-doubter like that."
Schroder shrugged his shoulders when asked about the location of the pitch.
"I wanted the fastball to get in on him," he said. "I left it over the middle."
Atkins homered on the first pitch he saw to make it 13-8.
After Soriano hit an RBI single off Ray King in the ninth, Brian Fuentes retired Felipe Lopez with two on for his 25th save in 30 chances.
The Rockies built a 4-0 lead after two innings. Holliday hit a two-run homer in the first and Matsui slapped a two-run double to right in the second.
The Nationals got five straight hits to start the third, including Logan's first home run of the year, but managed only two runs. Zimmerman had an RBI single.
Washington starter Pedro Astacio didn't make it out of the third.
Jeff Francis didn't get an out in the fifth, and Washington scored five times to tie the score at 7.
"I got a big lead and couldn't make pitches," said Francis, who was touched for six runs and 10 hits in four-plus innings. "I didn't deserve to win anything."
Colorado regained the lead in the fifth on Chris Iannetta's run-scoring single. The Nationals tied it again in the seventh on Logan's triple to left off Justin Hampson.
Astacio gave up six runs and five hits in 2 1/3 innings. He is winless in his last four starts. ... Former Washington 2B Jamey Carroll was out of Colorado's starting lineup. Carroll was 14-for-31 in seven games against the Nationals in 2006. ... The Rockies placed C Yorvit Torrealba on the 60-day disabled list and purchased the contract of C Alvin Colina from Double-A Tulsa. ... The Rockies outscored Washington 78-41 this season.