Seattle Seahawks rookie defensive end L.J. Collier is being evaluated for an ankle injury, a source told ’s Adam Schefter.

The team’s first-round draft pick left practice Tuesday on a cart. He was engaged with Duane Brown on a passing play when he went down in obvious pain.

Collier refused help off the field from the training staff and walked off on his own with a pronounced limp.

The Seahawks’ depth at defensive line has taken a hit this offseason with the trade of defensive Frank Clark and the six-game suspension of defensive tackle Jarran Reed.

’s Brady Henderson contributed to this report.