The Washington Nationals are going to have to do without Stephen Strasburg this weekend, but quality of starting pitching hasn't much mattered against the Atlanta Braves.

Tanner Roark takes the mound Friday night at Nationals Park as Atlanta's Julio Teheran tries to put possibly his worst start of the season behind him and end his club's longest losing streak in nine years.

Strasburg's ongoing health issues are pushing Roark (4-4, 4.54 ERA) into the rotation after being recalled from Double-A Harrisburg following Monday's abbreviated start.

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Strasburg (upper back tightness) threw an extended bullpen session Thursday and will likely return next week against the first-place New York Mets.

Roark made two starts in a brief stay in the minors to stretch out after being sent down Aug. 25, surrendering one run and five hits in six innings.

In the majors, he's pitched exclusively out of the bullpen since the beginning of July, and after some initial struggles posted a 1.93 ERA in 14 innings over his last nine outings. The right-hander's time in the rotation ended on a terrible note with eight runs and 12 hits allowed in 3 1-3 innings of an 8-5 loss in Philadelphia on June 28.

Teheran (9-7, 4.62) can relate. The right-hander gave up eight runs and nine hits with three home runs in 4 1-3 innings of Sunday's 20-6 home loss to the New York Yankees. The 24-year-old had gone 3-0 with a 2.73 ERA in his first five August starts, but the majority of that success came at home.

Away, Teheran is 2-5 with a 6.32 ERA in 13 outings, including one in Washington with six runs allowed in five innings of an 8-6 walk-off loss May 9. He is 2-1 with a 4.65 ERA in five starts at Nationals Park.

Bryce Harper is 9 for 21 with two home runs and three doubles when facing Teheran, and catcher Jose Lobaton (7 for 13 with two home runs) could also be in the lineup, though Wilson Ramos is on an 11-game hitting streak.

Roark is 3-0 with a 1.90 ERA in five starts and five relief efforts against the Braves. Jace Peterson (0 for 8), Andrelton Simmons (1 for 12) and Nick Markakis (1 for 6) have struggled in the matchup, but Freddie Freeman is 7 for 17.

Washington (68-65), six games back of New York, opened the series with Thursday's 15-1 win for its second-highest hit (18) and run totals of the year. Harper walked four times and scored four runs without swinging his bat, giving him nine walks and a .688 on-base percentage in the last four games.

It's benefited cleanup hitter Ryan Zimmerman, who's batting .405 with seven home runs, 23 RBIs and a 1.428 OPS in his last 11.

"That's why Bryce didn't swing at a pitch and scored four runs," manager Matt Williams said. "There's your proof in the pudding right there."

The Braves (54-80), having their worst season since 1990, have lost nine straight and 16 of 17. They last lost 10 in a row in 2006, and they're also in danger of dropping 11 straight on the road for the first time since 1977. The next stop might be last place in baseball's worst division with Philadelphia one game back.

Over a 3-20 span in which it hasn't won consecutive games, Atlanta is averaging 2.6 runs with a 6.64 ERA while giving up 15 or more runs three times in the last seven games.

"These guys are professional, they're major leaguers," Freeman said of Atlanta's staff. "Some of these guys have a lot of years playing in the minor leagues, and for them to get hit around like that is not really acceptable."

The Braves have lost seven straight in Washington.