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Make no mistake about it: The Houston Astros are tired of losing.

Perhaps no one expressed that sentiment better after their latest defeat Thursday night than infielder Marwin Gonzalez.

"How can everyday be the same?" Gonzalez pondered on his Twitter account.

He asked the same question in Spanish seconds later, for good measure.

Losing is getting old, indeed, for the Astros, who were shut out for the 11th time this season in a 5-0 loss to the surging Washington Nationals.

"Frustrating," said Astros starter Lucas Harrell, who lasted five innings.

Brett Wallace went 3 for 4 with a double and Justin Maxwell led a solid defensive effort with a pair of outstanding catches in center field.

But the Astros mustered little at the plate against Jordan Zimmermann and the NL East leaders, who completed a four-game sweep. The Nationals have won six straight and eight of nine.

Michael Morse homered twice while extending his hitting streak to a career-best 18 games, the longest active string in the majors, and Zimmermann (9-6) matched his career high for strikeouts with 11 in his sixth consecutive victory.

Washington beat the Astros twice in extra innings while earning its second series win at Minute Maid Park. The other one came in August 2007, when the Nationals took three of four.

The Astros own the worst record in baseball at 36-77 and are a dreadful 4-34 since June 27, a stretch that includes two wins in 15 home games.

It was their last game against Washington as National League brethren. Houston is moving to the AL West next season.

The loss, the first by shutout since July 20 at San Diego, marked the 10th time Houston was swept in a series.

"We want to win in the worst way," reliever Wilton Lopez said. "It just hasn't happened for us."

The Nationals are having no such problems.

Zimmermann had a field day with Houston, allowing just three hits over six innings. The Astros were outhit 12-5.

Harrell (9-8) gave up two runs and five hits over five innings. He struck out five and walked five in his first loss since July 19 at San Diego.

The two runs came in a 32-pitch fourth inning that included an RBI single by Adam LaRoche and a sacrifice fly by Morse.

"That fourth inning got him in trouble," Astros manager Brad Mills said. "He ran out of gas in that fourth inning. He was able to get through the fifth inning but wound up with 100 pitches. With where we were and last outing in Atlanta pushing him to 118 and with this max effort, the last thing we wanted to do was get him hurt."

The Nationals went on to load the bases with two outs, but Harrell was able to contain the damage by getting Zimmermann to line out to center.

"I made a few good pitches there in the fourth," Harrell said. "Just a few pitches here and there, and things would have been a lot different. That was the best I felt in probably my past four or five starts."

Washington picked up another run in the sixth when Morse homered to left off reliever Mickey Storey

Morse homered again in the eighth, this time off right-hander Fernando Rodriguez, to make it 4-0. It was Morse's 10th home run of the season. He finished 2 for 3 with three RBIs, one of four Nationals with multihit games.

Ryan Zimmerman's ninth-inning sacrifice fly drove in Cesar Izturis to cap the scoring.

Remember Gonzalez's tweet? He followed it with an explanation about how things were not going the Astros' way despite them playing and working hard every day.

"That will change tomorrow," Gonzalez said in closing.

The Astros can only hope.

NOTES: Houston optioned INF Matt Downs and OF J.D. Martinez to Triple-A Oklahoma City after the game. ... Nationals manager Davey Johnson gave rookie Bryce Harper a night off after he went 0 for 11 in the first three games of the series. Johnson said Harper will be back in the lineup Friday. "He's an intense competitor and sometimes, just like all young players, their emotions kind of get in the way of their ability sometimes. He just needed to sit back and relax and take it easy and he'll be fine," Johnson said. ... The Astros acquired INF Tyler Greene from St. Louis for a player to be named or cash. Greene was traveling to Houston on Thursday and will be activated for Friday's game.