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07/09/09 6:54 PM ET

Lannan to open second half for Nationals

Left-hander to be followed by Olsen for Cubs series

HOUSTON -- Nationals manager Manny Acta is already thinking about the second half and has announced that left-hander John Lannan will pitch the first game against the Cubs next Thursday at Nationals Park, while left-hander Scott Olsen will get the nod the next day.

Lannan is clearly Washington's best pitcher this year, going 6-5 with a 3.45 ERA entering Thursday's action. He has already pitched 107 innings and has a chance to pitch 200 this year. Lannan could become the first Nationals pitcher since Livan Hernandez in 2005 to throw at least 200 innings in a season.

"He has been able to go past five innings in almost every one of his outings. He has been very consistent," Acta said. "We are shooting for a guy like him to throw 200 innings, if possible. It would mean a lot. He was counted on in the plan and has stepped up."

Lannan and Olsen starting the first two games against the Cubs means that left-hander Ross Detwiler, who pitched on Wednesday against the Rockies, will be skipped in the rotation. Right-handers Jordan Zimmermann and Craig Stammen will likely pitch the third and fourth games, respectively.

Detwiler has been hit hard in his past three starts, giving up 16 runs in his past 12 1/3 innings. He is having problems keeping his fastball down in the strike zone. It would not come as a surprise if Detwiler was sent to Triple-A Syracuse to work on his mechanics.

Bill Ladson is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.