WASHINGTON -- Stephen Strasburg had just started to feel good on the mound when his manager told him he was finished for the day.

Making his second major league start since undergoing Tommy John surgery, Strasburg allowed one run over three innings in Washington's 8-2 win against the Houston Astros on Sunday.

After the right-hander worked a perfect third, Nationals manager Davey Johnson let him know he was coming out.

"I explained to him, 'Look, I don't want to have to go out and hook you during an inning, and as far as I'm concerned it was like your second time out in spring training,'" Johnson said. "That's enough for me."

Strasburg didn't display the same efficiency he did in his return Tuesday. He needed 31 pitches to get out of the first inning, although he settled down and finished with six straight outs. The top draft pick of 2009 allowed three hits and struck out four in his 57-pitch outing.

Johnson said his young star was on a 70-pitch limit, but he decided to pull him earlier, especially after Strasburg's velocity seemed to drop slightly in the second inning.

"He said, 'Just three?' I said, 'Yeah. Just three.' But I expected that," Johnson said.

Strasburg called the short outing "frustrating," but he also understood Johnson's caution.

"He has my best interests at heart, and I trust him 100 percent," Strasburg said. "I'm going to go out there until he says I'm done, and today he said I was done in the third."

Strasburg's pitch count was almost exactly the same as it was in his first start back, when he threw 56 pitches over five scoreless innings and struck out four against the Dodgers. It was clear from the start Sunday he wasn't going to cruise through the Astros' lineup the same way -- he needed nine pitches to strike out leadoff batter Jordan Schafer.

Strasburg went to a full count on the first three batters, although he struck out two of them. The other, No. 2 hitter Jimmy Paredes, singled on a grounder up the middle that went through Strasburg's legs and bounced off second base. The fourth batter, Carlos Lee, singled on a 2-2 fastball to score Paredes.

Strasburg also allowed a leadoff hit in the second inning to Matt Downs, then finished with six straight outs.

"If I wasn't on a pitch count, it would have been nice to go out there and pitch longer in the game," Strasburg said. "That's how it's going to be sometimes. You're not going to go out there and feel perfect every time."

Ian Desmond, Rick Ankiel and Ryan Zimmerman all homered off Houston starter Henry Sosa (2-4) to start the third inning. It was the first time the Nationals had hit back-to-back-to-back home runs since July 11, 2009, at Houston. That was also the last time the Astros had allowed three straight homers.

"I think the nicest thing about that was to finally have a lead," Desmond said. "The last few series we've been behind and we've all been kind of defensive. So today I wanted to make sure -- I think we all wanted to make sure -- that we stayed aggressive."

The Astros (49-97) tied the franchise mark for most losses in a season. They have lost 97 games three times, most recently in 1991.

"It speaks for itself," said outfielder J.D. Martinez, who was 0 for 3. "It was just one of those nights."

To mark the 10th anniversary of 9/11, Washington wore special blue jerseys with a stars-and-stripes background for the team's 'W' logo. Two red, blue and white logos were painted on the field in foul territory along the base lines, with the date "September 11, 2001" and the words: "We shall not forget."

Chris Marrero drove in two runs with a sacrifice fly in the second to tie the game and an RBI double in the third. Zimmerman and Desmond also had two RBIs each.

Tom Gorzelanny (3-6) followed Strasburg and pitched three scoreless innings, giving up one hit.

Sosa, making his seventh major league start, allowed five runs and seven hits in 2 2/3 innings, the first time he has failed to go at least five innings.

Game notes
Nationals 2B Danny Espinosa snapped an 0-for-15 slump with a double in the second inning. He was 2 for 4 with two doubles. ... Nationals rookies dressed in Smurfs costumes -- including blue body paint on their torsos -- after the game in a hazing ritual. ... Houston purchased the contract of LHP Xavier Cedeno from Triple-A Oklahoma City and placed LHP Sergio Escalona on the 60-day disabled list. Cedeno flew from Puerto Rico to join the team in Washington, although his luggage and equipment didn't arrive with him. "We'll get him some shoes and a glove and go from there," manager Brad Mills said before the game. ... The Nationals start a four-game series at the New York Mets on Monday. LHP Ross Detwiler (2-5) will start for Washington against RHP R.A. Dickey (8-11). ... Houston hosts Philadelphia on Monday. RHP Brett Myers (4-13) opposes Phillies RHP Roy Oswalt (7-8) in a matchup of pitchers facing their former teams.