Washington Nationals right-hander Stephen Strasburg will make his second rehab start Friday night for Class-A Potomac.

Strasburg underwent Tommy John surgery Sept. 3, 2010. He threw 31 pitches in his first rehab start on Sunday. The 23-year-old struck out four and gave up a solo home run over 1 2-3 innings.

He threw mostly fastballs, topping out in the upper-90s.

Nationals manager Davey Johnson said on Tuesday that Strasburg will throw three innings with a 50-pitch limit for Potomac.

"Stras is going to be on a normal program," Johnson said. "He'll go three innings on Friday with a limit of 50 pitches. He'll probably go the next time out, five days later, he'll go four innings, probably 60 pitches or something like that. Then he'll go five innings and 80 pitches and probably be ready to go."

Johnson said he still hopes to see Strasburg in the Major Leagues by early September to take the place of right-handed starter Jordan Zimmermann, who is on a 160-inning limit this season.

"He doesn't need to hear from me. He wants to see me," Johnson chuckled. "His time is coming, he just needs to be patient."

Washington general manager Mike Rizzo said the most important thing for Strasburg is to build arm strength.

"His arm is working great, he's mechanically sound," Rizzo said. "He's throwing free and easy and no pain. He's spinning his breaking ball well and his changeup is coming along. His stuff is coming along."