Second baseman Jose Vidro, the Washington Nationals' most dangerous clutch hitter over the course of his career, will begin a rehabilitation assignment at Class A Potomac today, his first competition since he injured his left ankle on May 4.

"I'm excited, not because I'm going back playing, but because I felt good out there running," Vidro said yesterday after taking batting practice and ground balls and going through some running drills at RFK Stadium. "So hopefully, I'm going to be back here in no time."

General Manager Jim Bowden said Vidro will begin his rehab by being the designated hitter and batting leadoff, a move designed to give him as many at-bats as possible. Bowden said Vidro could play in the field by the end of the weekend. He will be reevaluated on Monday, when the Nationals return from a three-game trip to Chicago, and is still expected back after the all-star break.

No Hearing Yet for Byrd

Outfielder Marlon Byrd was suspended for two games on June 9, but hasn't yet had his appeal heard by baseball officials, and therefore hasn't missed any time. Greg Bouris, a spokesman for the players' union, said yesterday the hearing hasn't yet been scheduled. . . .

Left-hander Joey Eischen, out since May 1 with a broken right arm, will be activated for tomorrow's game in Chicago.