Three of San Francisco's top four wide receivers are currently shelved with injuries, forcing the team to explore the free agent market for potential replacements. That's why free agent Austin Collie visited the team's headquarters in Santa Clara for a workout Thursday.
Michael Crabtree suffered a torn Achilles tendon in OTAs and will likely miss the majority of the season, if not all of 2013. Kyle Williams and Mario Manningham have yet to participate in any on field drills after suffering major injuries in 2012, forcing the team to look for depth elsewhere.
Both players are looking to return from ACL injuries, but Williams is expected to return for training camp while the timetable is still up in the air for Manningham, who suffered his injury in Week 16's 42-13 loss in Seattle.
Collie also visited with the New England Patriots this week. But his health remains a serious question mark after he missed 15 games with a ruptured patella tendon in 2012. Two years earlier, he suffered from a run of concussions that limited him to nine games.
If signed, there's a good chance Collie sees a significant number of snaps for the 49ers' offense. He'll be competing with second-year player A.J. Jenkins and rookie Quinton Patton to supplement Anquan Boldin, who was acquired via trade early in the offseason with the Baltimore Ravens.
Collie combined for 15 touchdown receptions in his first two years in Indianapolis with Peyton Manning at quarterback. He was drafted in the fourth round in 2009.
Replacing Crabtree's production won't be easy for San Francisco's offense after he became Colin Kaepernick's favorite target in key situations. The former 10th-overall posted career highs with nine touchdown receptions and 1,105 receiving yards in 2012.