The San Diego Chargers have traded up in the

NFL draft to take LaDainian Tomlinson's heir apparent, Fresno State running back Ryan Mathews, with the No. 12 pick overall.

The Chargers had been set to pick No. 28 but traded up to get Mathews.

Mathews is expected to replace Tomlinson, who was released in February after nine brilliant seasons in which he became one of the greatest running backs in NFL history.