The news comes almost 30 minutes after Estrada called a great game in a 1-0 defeat. The Nationals had four catchers on the 25-man roster and some one had to go.
Estrada has 10 days to be either traded or claimed off waivers. Once those 10 days are up, Estrada could be released or outrighted to the Minor Leagues. Estrada said he will not go the Minor Leagues and is ready to go home to Atlanta.
Estrada, 32, batted .170 with four RBIs in 23 games with Washington. He missed 69 games this season because of a right elbow injury.
"Mentally, I'm ready to go home. It has been a grind for me all year. I've been hurt. This is the first time, I've been hurt," Estrada said.
Milledge, who had been on the disabled list since June 28 because of a right groin strain, was promoted to Triple-A Columbus on Tuesday after playing two games for Rookie-level Gulf Coast. Milledge was 1-for-4 with a home run for the GC Nationals and was 1-for-8 for the Clippers.
Bill Ladson is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.