Patriots believe top draft pick Derek Rivers has season-ending injury, report says

The Patriots believe defensive end Derek Rivers, their top draft pick this year, will miss his rookie season with a knee injury, ESPN reported Friday.

NFL Media later reported an MRI showed Rivers tore the anterior cruciate ligament and sprained the lateral collateral ligament in his left knee.

Rivers, a third-round pick out of Youngstown State, was injured on a kickoff coverage drill during the Patriots' joint practice with the Texans on Wednesday in West Virginia. The team sent him back to Boston for more testing and apparently the results were not good.

Rivers had 41 sacks in his college career, including 14 last fall as a senior. The Patriots were counting on him to be a regular contributor up front, if not necessarily a starter right out of the gate.

With the rookie out of the mix, the depth chart at defensive end is looking thin: Kony Ealy, Trey Flowers, Geneo Grissom and Caleb Kidder, the latter an undrafted free agent. That could mean the Patriots are in the market for veteran help at the position as the regular season approaches.