The Steelers officially ruled Williams out after Friday's brief workout. Williams had been considered unlikely to play in the AFC wild-card round matchup against the rival Bengals since suffering the injury in Sunday's regular-season finale.
Williams intends to return to action fully next week in the divisional round if the Steelers beat the Bengals on Saturday night, a source told ESPN's Jeremy Fowler.
Steelers offensive coordinator Todd Haley said Thursday that running back Fitzgerald Toussaint will be "the guy" this week unless Williams can play. Haley also said running back Jordan Todman will be heavily involved in the offense.
The Steelers feel more confident in this crop of reserve tailbacks compared to last year's playoffs, when Pittsburgh signed Ben Tate off the street days before an AFC wild-card loss to Baltimore. The trio of Tate, Dri Archer and Josh Harris combined for 43 yards on 15 carries; all three players currently are out of the league.
Steelers wide receiver Markus Wheaton believes Toussaint and Todman are quality tailbacks.
"They just haven't been seen yet," Wheaton said. "I feel we can run the ball really well, even without DeAngelo."
Asked about the reason for optimism with this tailback crew, H-back Will Johnson nodded to Toussaint's locker, saying he's earned everyone's trust.
Even though the yards aren't there (42 yards on 18 carries), Johnson said the film doesn't lie with Toussaint, who's in the right place on every run. Coach Mike Tomlin calls Toussaint a "talented, blue-collar runner" and capable pass protector.
ESPN's Jeremy Fowler contributed to this report.