Washington said Hamilton would be available to pinch-hit. Third baseman Adrian Beltre batted third in place of Hamilton, and rookie Leonys Martin was set to start in left field.
Hamilton was upbeat in the clubhouse before the game. The 2010 AL MVP prepared as if he were starting, spending a couple of hours taking swings in the batting cage.
It was the first time Hamilton was out of the starting lineup since June 17, when he missed three games with an intestinal virus.
"I just thought he needed a mental break," Washington said. "It was time that I give him a break."
Hamilton said he's also battling some physical problems, but didn't specify any injury.
"It's a compilation of things," he said.
Team president Nolan Ryan was critical of Hamilton's approach at the plate during a radio interview Monday. Then the slugger heard the rare boos from his home fans on Friday.
The jeers were scattered after he struck out in the third inning against Sale. The booing became louder when he went down on three pitches in the fifth.
Hamilton also misplayed a fly ball in left that led to a White Sox run in the first inning.
Despite the difficult week, Hamilton remains confident he will turn things around.
"It's going to be good, folks," he said. "Fans out there, it's going to be good. Just hang in there."
After a torrid start, Hamilton was hitting .190 with seven home runs and 26 RBIs since June 1. His batting average had dropped from .368 to .284 during that span.
Despite the prolonged slump, Hamilton entered Saturday tied for the American League lead in RBIs with 83 and tied for second in home runs with 28.