The loss was the third in a row for the defending champion Shock (1-3), who opened the season with a victory at San Antonio and have followed with losses to New York, Los Angeles and Washington.
A three-point play by Cheryl Ford gave the Shock a 61-59 advantage with 1:14 left. But rookie Alana Beard tied the game with a layup with 56.4 seconds remaining and Holdsclaw converted a pair of free throws with 28.2 seconds left to give Washington the lead for good.
A free throw by Holdsclaw increased the lead to 64-61 with 11.6 seconds remaining, but Swin Cash scored inside to pull Detroit within one with 5.3 seconds left.
After Holdsclaw again made 1-of-2 free throws with five seconds remaining, Detroit's Deanna Nolan missed a desperation shot from midcourt.
Holdsclaw finished with 16 points and 14 rebounds and Beard added 16 points.