Tough news out of 49ers rookie minicamp this week, as former Notre Dame linebacker and fifth-round draft pick Darius Fleming tore an anterior cruciate ligament and could miss his rookie season, according to NFL.com's Ian Rapoport.

Fleming's agent, Andy Simms, told Rapoport that the ACL was the only ligament Fleming tore.

Fleming, a 6-foot-1, 245-pounder from Notre Dame suffered the injury in a non-contact drill, coming down on his knee awkwardly. He attempted to continue doing drills, but quickly realized his knee was giving out. He had an MRI, which confirmed the injury.

Fleming had signed his contract Thursday, a day before suffering the injury. When fellow Irish linebacker and good friend Steve Filer went down with the a similar injury in November, ending his college career, Fleming wore Filer's No. 46 jersey for the Nov. 12 game against Maryland. Here's hoping for a quick recovery for Fleming, one of the better guys both on and off the field from last year's Notre Dame team.