Duffy (Achilles) will resume his rehab assignment Thursday with High-A Charlotte, Marc Topkin of the Tampa Bay Times reports.
Duffy hasn't played a big league game since June 19 but appears to be close to finally making his return. The 25-year-old will likely play a few more rehab games at various levels before making his Rays debut. Duffy has been highly effective against southpaws this season, hitting .290 with two home runs and five RBI in 69 at-bats and could see time at all four infield positions once he is healthy.