Buffalo Bills linebacker Kiko Alonso tore his ACL while working out privately in Oregon.
The Bills will be without one of their best defenders for the 2014 NFL season, as ACL surgery takes seven-nine months to recover from, according to ESPN.
General manager Doug Whaley said in a statement on the Bills website, that the Alonso will miss the season, and the team feels bad because he worked very hard in the offseason.
He was recovering from hip surgery in January to repair a torn labrum and he was expected to be ready for training camp in July.
Alonso was expected to move to weakside linebacker with the signing of Brandon Spikes, the Bills will now have to find a player to replace Alonso, according to NFL.com.
Alonso was coming off a rookie season that saw him rank third in the NFL with 159 tackles, finishing second in the AP NFL defensive rookie of the year voting.
Alonso was a second round pick from the University of Oregon in 2013. In addition to his tackles, Alonso had two sacks, four interceptions, one forced fumble and four passes defended, according to The Sports Xchange.