Matsui (groin) was recently cleared to resume throwing off a mound, and he participated in defensive drills Monday, Kevin Acee of The San Diego Union-Tribune reports.
Matsui's availability for Opening Day remains a big question mark, but the fact that he's slowly beginning to ramp back up is a positive sign. He'll presumably need to complete at leasts a few additional side sessions before San Diego considers deploying him in a Cactus League game.