Troy Merritt earned a share of the lead with Kevin Chappell after shooting a tournament-record 61 on day three of the Quicken Loans National.
The American fired an ominous warning to his rivals in Virginia by holing 11 birdies to card a 10-under-par round and move level with compatriot Chappell on 14-under.
Rickie Fowler sits one stroke behind, while Jason Bohn, Whee Kim, Charles Howell III and David Lingmerth go into the final day just two shots off the pace.
Tiger Woods was tipped for a solid Saturday after posting his lowest 36-hole total in two years over the first two days.
However, the 14-time Major winner and world number 266 endured a disappointing round of 74 as he sits nine off the pace on five under.
Elsewhere, Justin Rose's 65 catapulted him into contention as the Englishman finds himself three adrift.
