Washington Nationals manager Davey Johnson announced Saturday morning that ace right-hander Stephen Strasburg has been shut down, effective immediately.

Initially, it appeared Strasburg would make one additional start, but Johnson made the decision to end his season after Friday's game against the Marlins.

Strasburg allowed five runs on six hits, while walking three and striking out two in just three innings of work. Without question, it was one of Strasburg's weakest showings of the season.

After Friday night's contest, Strasburg has pitched 159 innings on the season. It had been believed all along that the Nationals would shut down Strasburg at around 160 innings.

Strasburg ends the 2012 season with a 15-6 record in 28 starts. Strasburg struck out 197 batters, while walking 48, and limiting opponents to an average of .230.

The decision to shut down Strasburg was one of the most hotly debated topics of the past month, as the Nationals continue to push toward an NL East crown and postseason play.

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