Updated Oct 13, 2010 8:40 PM ET
The San Diego Chargers have placed starting OLB Shawne Merriman (calf) on injured reserve with the minor injury designation. The rarely used designation means Merrimanís recovery from his injury is less than six weeks.
Merriman, by rule, must be released by the Chargers once heís healthy.
Merriman, 26, was selected in the first round of the 2005 NFL Draft by the Chargers.
Merriman saw limited action in the seasonís first five weeks. An Achilles injury forced him to miss the season opener in Kansas City. He saw limited action in Week 2 versus the Jacksonville Jaguars. He suffered a calf injury in Week 3 at Seattle and missed the teamís victory over the Arizona Cardinals in Week 4. He re-injured his calf last week in Oakland.
The Chargers now list four linebackers on injured reserve: Donald Butler, James Holt, Jyles Tucker and Merriman. OLB Larry English (foot) also has missed three games and is expected to miss 2-4 more weeks.
The Chargers have signed OLB Antwan Barnes, who was waived by the Philadelphia Eagles on Oct. 9.
A team to keep an eye on once Merriman becomes healthy are the San Francisco 49ers. San Francisco, like San Diego, runs a 3-4 defensive scheme.