WASHINGTON -- Colorado Rockies manager Walt Weiss called Michael Cuddyer "one of the better kept secrets in the game."

That perception might change soon.

Cuddyer homered in his first at-bat to extend the major league's longest hitting streak this season to 21 games -- and the Rockies hung on to beat the Washington Nationals 7-6 Sunday.

Cuddyer went 3 for 4 with four RBIs to break a tie with St. Louis Cardinals third baseman David Freese for the year's top streak, and the Rockies right fielder is now just two games shy of matching the franchise's best run. Dante Bichette, now the team's hitting coach, had hits in 23 consecutive games in 1995.

Cuddyer also extended his Colorado record for consecutive games reaching base to 40.

And if all that means he gets more recognition, he wouldn't mind.

"After 12 years of being in the big leagues, you don't like to think of yourself as a secret," Cuddyer said with a laugh.

Not that he would mind remaining under the radar, either.

"He doesn't care about that stuff," Weiss said. "He likes to show up, compete and work on his beard. That's all that matters to Cuddy."

With his wife and son in attendance, Cuddyer, a Virginia native, had an RBI single in Colorado's three-run third inning and a two-run single in a three-run fourth, an inning Nolan Arenado led off with a homer.

That gave Jorge De La Rosa (8-4) a 7-0 cushion. He allowed seven hits in six innings, trading both his earned runs for outs in the bottom of the fourth.

In his shortest start this year aside from a May outing he left early due to lower-back spasms, Ross Detwiler (2-6) allowed a season-high seven earned runs -- three more than any other game.

Washington right fielder Jayson Werth started after missing Saturday's game with flu-like symptoms, but he left in the fourth inning following his second hit. Werth stretched his left leg on first base before gesturing to the dugout for a pinch runner.

"I think I'll be all right," Werth said. "Groins are pretty straight forward. I've had a couple of them in the past, but never missed any time, so I'm hoping that will be the case."

Colorado left fielder Carlos Gonzalez left the game in the middle of the eighth inning with a leg cramp.

Washington third baseman Ryan Zimmerman had an RBI infield single in the bottom of the eighth, and a second run scored on the play when Rockies short stop Josh Rutledge booted the ball. Jhonatan Solano pinch hit and lined a two-out, two-run double to centerfield.

But Rex Brothers struck out Ian Desmond and threw a perfect ninth, ensuring the Nationals' four-run eighth left them still a run short. Brothers' fourth save was also Colorado's first four-out save of the season.

"I try not to show much emotion in there," Weiss said. "But you know that, deep down, you've got to put this game away. You've got put this game away, because wins are precious in this league, and when you get out to a lead like that, you've got to put it away, because it's going to be tough enough to win in this league as it is."

If the Rockies were looking for a stabilizing influence during their up-and-down game, Cuddyer sounds as if he could have provided it.

"That's the thing about hitting streaks," Cuddyer said. "The day it's over, you go back to being a baseball player."

NOTES: Nationals manager Davey Johnson said RHP Dan Haren is headed to the disabled list. Haren, who surrendered six earned runs in 3 1/3 innings Saturday to drop to 4-9 with a 6.15 ERA, said his shoulder has been bothering him his last few starts. "Nothing really major," Haren said. "Nothing I haven't pitched through in the past. I'm not concerned about it, but they wanted me to take some time to get 100 percent." He said he'll probably have an MRI this week. ... Washington OF Bryce Harper took full on-field batting practice for the first time since going on the disabled list June 1 (left knee bursitis). With fans arriving early to Nationals Park to receive Harper bobbleheads, he sent multiple pitches over the outfield wall. Before the game, Harper tweeted, "Well that felt unreal! #BP #Lovethefans." Arenado has missed only one game since the Rockies called him up from Triple-A Colorado Springs in late April, and Weiss said it's difficult to find days off for the rookie. "He's wound too tight," Weiss said. "He doesn't like to sit over here for nine innings." ... Weiss said he planned days in advance to give Todd Helton both Saturday and Sunday off. The Rockies don't play Monday, so the first baseman will get three straight days of rest. ... Colorado RHP Juan Nicasio (4-3, 4.78) will face Boston Red Sox RHP Ryan Dempster (4-8, 4.23) on Tuesday. ... Nationals LHP Gio Gonzalez (3-3, 3.34) will face Arizona Diamondbacks RHP Trevor Cahill (3-8, 3.92) on Tuesday. ... Rapper Wale, a D.C. native, threw out the ceremonial first pitch.