ASHBURN, Va. -- Newly acquired Washington Commanders cornerback Marshon Lattimore and starting running back Brian Robinson Jr. have been ruled out for Sunday's game vs. Pittsburgh.

Both players are dealing with hamstring injuries and neither played last week. Lattimore missed his last game with New Orleans before the team traded him Tuesday; Robinson sat out Washington's win at the New York Giants.

Robinson, who was limited during Wednesday and Thursday practices, did not practice Friday.

The Commanders will also be without offensive tackle Cornelius Lucas for a second straight game as he deals with an ankle injury. Kicker Austin Seibert, who kicked in practice Friday after being limited Thursday and not practicing Wednesday due to a hip injury, is questionable. The team signed Zane Gonzalez to the practice squad as insurance if Seibert can't kick.

Washington traded three picks to the Saints to acquire Lattimore, sending them third-, fourth- and sixth-round selections and getting back a fifth-round choice. But the Commanders were clear from the beginning that they weren't sure when Lattimore would be able to play.

"We're always going to side on the health of the player first," Washington coach Dan Quinn said.

Lattimore missed the Saints' Week 2 game with Dallas this season because of a hamstring injury. Washington wants to make sure he's healthy for the rest of the season.

Washington plays at Philadelphia on Thursday. Lattimore worked with trainers on a separate field during practice Friday, but Quinn said they'd have a better assessment Monday of his chances to play vs. the Eagles.

Robinson already has missed two games this season,, though he still leads the Commanders with 461 yards rushing and six touchdowns.

Washington will use a rotation at running back in Robinson's absence, starting with Austin Ekeler and Jeremy McNichols. The Commanders also could promote another running back off the practice squad.

They have elevated Chris Rodriguez Jr., three times already so if they do so again, according to the NFL rules regarding the practice squad, he would have to remain on the active roster if promoted again. They could also opt to elevate Michael Wiley off the practice squad.