Rookie quarterback Geno Smith will not play in the Jets' second preseason game against the Jaguars on Saturday night, the team announced on Twitter.
Smith, a second-round draft pick out of West Virginia, injured his ankle in the third quarter of the team's game against the Lions last Friday after completing six of seven passes for 47 yards in his NFL debut.
Mark Sanchez will start at quarterback and is expected to play the first half.
After impressing early, Smith struggled during what head coach Rex Ryan called a "brutal" practice following the injury on Wednesday. Sanchez completed 10 of 13 passes for 125 yards and a touchdown in the preseason opener, but threw an interception that was returned for a touchdown.