Washington @ Arizona preview

Last Meeting ( Aug 10, 2012 ) Washington 9, Arizona 1

The Nationals are fast becoming the team nobody wants to face in the playoffs, and Arizona is learning that the hard way. One game after being held to one run by Stephen Strasburg and three relievers, the Diamondbacks look to snap the Nationals’ seven-game winning streak on Saturday. Arizona has lost three straight to Washington, and the team has dropped five of seven overall. Washington rookie Bryce Harper went 0-for-2 on Friday, and he’s hitting just .173 (18-for-104) since the All-Star break. Manager Davey Johnson said Harper will get Saturday off and return for Sunday’s series finale.

While Washington became the first team in the majors to reach 70 wins on Friday, Arizona remained four games out of first in the National League West. The Diamondbacks made a minor deal just before last month’s trade deadline, but it’s paying major dividends. Third baseman Chris Johnson has made a seamless transition since being acquired from Houston, batting 14-for-42 (.333) in 11 games since the July 29 trade and relegating rookie Ryan Wheeler to a backup role. Wheeler has just four hits in 22 at-bats since being called up from Triple-A Reno, where he was hitting .351 with 15 homers.

TV: 8:10 p.m. ET, MASN2 (Washington), FS Arizona (Arizona)

PITCHING MATCHUP: Nationals RH Edwin Jackson (6-7, 3.56 ERA) vs. Diamondbacks LH Wade Miley (12-7, 2.85)

Jackson gave up two runs on two hits over 5 1/3 innings last Monday against the Astros, and has failed to pitch through the sixth inning in each of his last two starts. Jackson, who made 21 starts for the Diamondbacks in 2010, is 4-6 with a 5.24 ERA in 15 career appearances (14 starts) at Chase Field. Aaron Hill is batting .194 (7-for-36) in his career against Jackson.

Miley is a major reason why Arizona has remained in postseason contention, and is also a strong contender for the National League rookie of the year award. He has won three of his past five starts while allowing just one home run during that span. Miley is 7-3 with a 2.76 ERA in 11 outings (nine starts) at Chase Field this season.

WALK-OFFS

1. Arizona placed RHP Josh Collmenter (ulcers) on the disabled list and recalled RHP Brad Bergesen from Triple-A Reno.

2. Washington LF Mike Morse had an 18-game hitting streak before a scoring change made Friday turned his hit on Aug. 2 into an error. His current streak stands at eight games after the change.

3. Diamondbacks SS Willie Bloomquist remains day-to-day with back stiffness, but he’s hoping to avoid a stint on the disabled list.