Las Vegas Raiders tight end Darren Waller, who was added to the injury report Saturday with an ankle issue, doesn't "feel great," and the team is not expected to know until pregame warm-ups whether he can play Sunday against the Philadelphia Eagles, a source told ESPN.

Waller strained the inner side of the ankle and heel during practice Friday, when he was tripped by a teammate, according to a source who saw the play. The Raiders considered the injury serious enough to list Waller as questionable for Sunday's home game.

The absence of Waller would be a setback to a Raiders offense that rallied around interim head coach Rich Bisaccia during his NFL coaching debut last Sunday in a 34-24 win over the Broncos in Denver.

Without Waller, the Raiders would have to lean more on backup tight end Foster Moreau, who has four receptions for 53 yards and a touchdown this season.

The Raiders think Moreau can be effective, but Waller has emerged as one of the NFL's top offensive threats, a player whom former Raiders coach Jon Gruden called "the best player I've ever coached" earlier this year.

Waller, 29, has a team-leading 33 receptions for 378 yards and two touchdowns in six games this season, his fourth with the Raiders. He set a Raiders single-season franchise record last season with 107 catches.