The Nationals will place right-hander Ryan Drese on the disabled list, retroactive to Aug. 19, and recall right-hander Travis Hughes from Class AAA New Orleans today.

The move comes after Drese complained of tightness in his shoulder. An MRI exam revealed tendinitis, and he will be lost for at least two starts. Left-hander John Halama will likely take Drese's next start, which was scheduled for Saturday against the St. Louis Cardinals.

Prior to last night's 6-2 loss to Cincinnati, Drese said tightness in his shoulder could be preventing him from raising his arm properly, a key element in throwing his sinker.

"It's been tight for a while now," said Drese, who is 3-6 with a 4.98 ERA and has lost his last five decisions.

Halama, signed as a minor league free agent, has pitched seven innings for the Nationals and is yet to allow a run. He would be the Nationals' first left-handed starter.

Hughes was 2-4 with 12 saves and a 2.65 ERA in 49 appearances for New Orleans. He pitched 41/3 innings for the Nationals earlier this year and didn't allow a run. He'll be used in the bullpen.

Zimmerman's Call-Up Is Imminent

General Manager Jim Bowden said top prospect Ryan Zimmerman will be called up "very soon," perhaps even today, and will be on the Nationals' playoff roster should the team qualify for the postseason.

The Nationals moved Zimmerman, who played third base his entire career at the University of Virginia, to shortstop at Class AA Harrisburg last week so that he would be prepared to play either position.

"He's a player we think can help us in a pennant race," Bowden said. "He will be here."

Zimmerman was hitting .312 with eight homers and 29 RBI in 55 games for Harrisburg. . . .

Outfielder Brad Wilkerson arrived at the ballpark yesterday, but departed before game time with what the club said was sinusitis. Ryan Church had already been posted in the lineup leading off, Wilkerson's normal spot, for the second straight game. Bowden said Wilkerson's condition was contagious.