HOUSTON -- Michael Morse homered twice, Jordan Zimmermann matched his career high with 11 strikeouts and the Washington Nationals completed a four-game sweep of the Houston Astros with a 5-0 victory Thursday night.
Morse drove in three runs and extended his hitting streak to a career-best 18 games, the longest active string in the majors after Miami's Jose Reyes was stopped at 26 games earlier in the day. Zimmermann (9-6) pitched six innings of three-hit ball before three relievers finished Washington's seventh shutout of the season.
The NL East-leading Nationals have won six in a row and own baseball's best record at 69-43.
Adam LaRoche drove in a run in the fourth inning before a sacrifice fly by Morse made it 2-0.
Morse's towering shot to left made it 3-0 in the sixth. He sent his second home run the opposite way to the seats in right field in the eighth for his fourth career multihomer game.
Zimmermann walked none in his first win over Houston in four outings. Michael Gonzalez, Sean Burnett and Drew Storen completed the five-hitter.
It was the 11th time this season the Astros were shut out and the first since July 20.
Lucas Harrell (9-8) yielded five hits and two runs with five walks in five innings as Houston dropped its fifth straight.
Zimmermann had retired seven straight, including striking out the side in the fifth, before Marwin Gonzalez singled with one out in the sixth. The right-hander got right back on track after that, fanning Steve Pearce and Justin Maxwell to end the inning.
Roger Bernadina singled to open the fourth before Ryan Zimmerman walked to set up LaRoche's RBI single. Morse's sacrifice fly added a run, but Harrell was able to limit the damage after that thanks in part to Maxwell robbing Jayson Werth of a hit by racing up Tal's Hill in center field to make a great catch.
Harrell needed 32 pitches to get through that inning, however, and was lifted for a pinch-hitter in the fifth.
Morse's first homer was off Mickey Storey, and Fernando Rodriguez gave up the second one.
Washington added a run on Zimmerman's sacrifice fly in the ninth inning.
NOTES: 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 was expected to suit up for the Astros on Friday.