
Roddick posted an internet message on his Twitter site saying he will take part in the hardcourt event that runs from August 2-9.
"I keep getting asked when my next tourney will be.... I will see all of u in Washington in two weeks," Roddick wrote in a posting, known as a tweet.
Roddick, the 2003 US Open champion, pulled out of the US Davis Cup quarter-final tie at Croatia the week after Wimbledon with a right hip injury and also pulled out of this week's ATP event at Indianapolis.
Roddick tumbled on the grass at the All-England Club in the fourth set in the final on July 5 but played more than 95 more minutes through the longest fifth set in Grand Slam final history before losing to the Swiss star 5-7, 7-6 (8/6), 7-6 (7/5), 3-6, 16-14.
Federer won a sixth Wimbledon title and record 15th Grand Slam title but needed four hours and 16 minutes to subdue Roddick.