After Adam LaRoche singled off Chad Gaudin (3-2) to open the inning, Desmond singled him to third and Danny Espinosa was intentionally walked to load the bases. With the infield in, Kurt Suzuki grounded into a fielder's choice as LaRoche was thrown out at home, but Brown followed with a bloop single to right.
"You can see the talent we have on this team," Brown said. "It's tough to pitch around anybody. I was fortunate enough to be in the right place at the right time and it felt good that I was able to get the job done."
The Nationals remained 6½ games ahead of Atlanta in the NL East. The Braves beat the New York Mets 11-3 later Saturday.
Drew Storen (2-1) pitched a scoreless 10th inning for the win.
"Once I got (the count) to 2-2, I figured he wasn't gonna mess around with any breaking stuff," Werth said. "He's got a good fastball, he likes to work up in the zone. I got a pitch that was up just enough."
Nationals manager Davey Johnson announced before the game that rather than having Strasburg finish his season Wednesday in New York as planned, they were shutting him down immediately.
"He's had a great year. I know what he's going through," Johnson said before the game. "The media hype on this thing has been unbelievable. I feel it's as hard for him as it would be anybody to get mentally, totally committed in the ballgame. And he's reached his innings limit. So we can get past this and talk about other things for a change."
Strasburg admitted he was disappointed with the decision.
"I thought I had another start," he said after the game. "It was pretty shocking and honestly, I'm not too happy about it."
The 24-year-old right-hander said he tried to talk his way into one more start.
"I talked to them about it and they seemed pretty firm," Strasburg said. "It's not just about me. It's not about one player. I think the best thing I can do now is move forward and be the best teammate I can."
Johnson said John Lannan will make the Wednesday start and remain in the starting rotation.
Strasburg allowed five runs and matched his career low by lasting only three innings in the Nationals' 9-7, 10-inning loss to the Marlins on Friday night.
"I sensed if from almost the first pitch of the ballgame yesterday, that that was gonna be it for him," Johnson said. "I discussed it with (pitching coach) Steve McCatty and (GM) Mike Rizzo and they were in agreement."
Strasburg finished 15-6 with a 3.16 ERA in his first full season following elbow-ligament replacement surgery on Sept. 3, 2010. He struck out 197 in 159 1/3 innings.
"I don't know if I'm ever gonna accept it to be honest," Strasburg said of the plan to end his season prematurely. "It's something that I'm not happy about at all. That's not why I play the game. I play the game to be a good teammate and win.
"You don't grow up dreaming of playing in the big leagues to get shut down when the games start to matter. It's gonna be a tough one to swallow, but like I said, all I can do is be the best teammate possible for these guys."
Ryan Zimmerman's 20th homer of the season, a two-run shot to left-center off reliever A.J. Ramos with no outs in the eighth, cut Miami's lead to 6-5. Michael Morse and LaRoche followed with singles, but the Nationals eventually left the bases loaded.
Jesus Flores' homer to left in the bottom of the third made it 3-1 and the Nationals got to within one in the fourth when Espinosa singled home Zimmerman.
Miami scored two unearned runs against Detwiler in the fifth. Solano led off with a walk and, with two outs, Carlos Lee walked. When LaRoche was unable to come up with Justin Rodriguez's sharp grounder at first, Solano scored on the error and Lee went to third. John Buck's single scored Lee.
Bryce Harper's solo blast into the upper deck in right-center field in the fifth made it 5-3.
The Marlins added a run in the seventh as Solano doubled and scored on Zimmerman's throwing error on Ruggiano's grounder.
Espinosa extended his hitting streak to 10 games. ... Buehrle (1,503) became the 24th active pitcher with at least 1,500 career strikeouts. ... Nationals pitcher Gio Gonzalez was ejected after arguing from the dugout with the home plate umpire following Stanton's homer. ... Washington's Edwin Jackson (9-9, 3.63) faces Ricky Nolasco (11-12, 4.64) in Sunday's series finale.