Twins' catcher Joe Mauer will stay on the disabled list Thursday despite being eligible to come off the disabled list because General Manager Bill Smith says he's not ready to return yet.  Smith says Mauer was set back a week in his recovery because of a viral infection.  Mauer is on the DL with leg weakness.  The Twins haven't decided whether Mauer will go on a rehab assignment when he's ready.  Smith says 2nd baseman Tsuyoshi Nishioka is making progress and is rehabbing in the pool but is still a ways away from returning.  Kevin Slowey is expected to throw approximately 45 pitches in a minor league game tonight.  He is nearing a return.