David Lingmerth shot a seven-under-par 65 to take a one-stroke lead into Saturday's session at the Memorial Tournament in Ohio.
The Swede managed seven birdies in a bogey-free round to boost his hopes of a first PGA Tour victory - and first professional win since 2012 - as he sits at the summit on 12 under.
Lingmerth is one shot clear of Jason Dufner, who holed two eagles for the second day in succession but a double-bogey on 12 ensured that the American is one off the pace heading into the weekend.
Matsuyama is one of six players currently tied for fourth, with one-time major winner Justin Rose among them.
Bo Van Pelt, whose eight-under-par 64 saw him share the lead with his Japanese counterpart after day one, fired a costly 72.