ATLANTA -- Nationals right-hander Jordan Zimmermann will start against the Astros on Tuesday. However, Zimmermann will continue to go on his regular rotation until he reaches 160 innings, according to manager Davey Johnson.

Zimmermann is already at 115 innings and is expected to make seven more starts this season. The original plan was to have Zimmermann get a lot of rest between starts after the All-Star break.

"I wasn't sure that was the best way to finish out this year," Johnson said. "I think regular work, regular side throwing until he runs out of innings, and then let him rest."

Zimmerman is clearly the Nats' best pitcher this season. He is 6-7 with a 2.66 ERA in 18 starts and leads the team with 82 strikeouts entering Friday's game.

Strasburg throws live BP for first time this year

ATLANTA -- The Nationals received great news Wednesday. Right-hander Stephen Strasburg threw live batting practice for the first time this season. He threw 45 pitches without any problems.

Strasburg is expected to have a similar session on Monday in Viera, Fla. General manager Mike Rizzo hasn't ruled out Strasburg pitching during the month of September. Strasburg has missed most of the season because of Tommy John surgery last September.

"If his rehab progresses on schedule, there is a chance he could get a Major League start in September," Rizzo said. "We want to build him up no matter where he is at -- around 50 or so innings this season to prepare him for next season."

Strasburg is considered the future ace of Washington's pitching staff. In his short stint with the Nationals last year, the No. 1 overall pick in the 2009 First-Year Player Draft was 5-3 with a 2.91 ERA in 12 starts. He struck out 92 in 68 innings.

Wang tosses six scoreless innings in Minors

ATLANTA -- Nationals right-hander Chien-Ming Wang pitched six scoreless innings for Double-A Harrisburg in a 3-1 victory over Akron on Thursday. His fastball was clocked as high as 94 miles per hour.

The big test for Wang is to throw 90 to 100 pitches, according to general manager Mike Rizzo.

"It's not the innings, it's the amount of pitches. That would be the next mile marker," Rizzo said. "As always is the case, it's the day or two after he throws [that are] the important days -- to see if he can bounce back. So far, he has. If he continues to do that ... then we are in good shape. "

Wang is out of Minor League options, so he will likely join the big league club when his rehab stint is over.

Wang has missed more than two years because of shoulder problems. The right-hander is in his second season with the Nationals, and hasn't pitched an inning for them in the big leagues.

Hairston starts rehab assignment in Double-A

ATLANTA -- Infielder/outfielder Jerry Hairston Jr., on the disabled list because of a fractured right wrist, started a rehab assignment for Double-A Harrisburg on Friday. He was expected to play seven innings and nine innings the next two games.

Hairston most likely will come off the DL when the Nationals go to Houston to play a three-game series against the Astros beginning Monday.

In 69 games for Washington this season, Hairston is hitting .260 with two home runs and 17 RBIs.