SAN FRANCISCO -- Jeremy Hefner occupies Johan Santana's rotation spot for a second turn in Monday night's series opener against the Giants, but Santana is moving closer to a return.

Santana is scheduled to throw a full-fledged bullpen session Thursday for the first time since landing on the disabled list.

Officially, Santana is on the disabled list with a sprained right ankle. But team officials contend the ankle injury prompted Santana to throw with his arm only, sapping strength from his surgically repaired shoulder.

Santana should return to major league action during next week's home stand. Team officials previously have identified Aug. 8 or 9 against the Marlins for Santana's return.