San Francisco ? San Francisco closer Armando Benitez is done for the season because of inflammation in his right knee.

The Giants planned to place the right-hander on the 60-day disabled list Thursday, after the club said Tuesday it hoped he could come back before the end of the year. Benitez returned to Miami on Wednesday to begin physical therapy.

To fill the roster spot, San Francisco will purchase the contract of right-hander Billy Sadler from Triple-A Fresno – though he has been home in Florida since the Grizzlies’ season ended. The Giants expect the pitcher to be in town for Thursday’s afternoon game, the series finale against the Colorado Rockies. Benitez had been unable to pitch for eight straight games because of sore knees. By making the move now, the Giants hope he will be ready by spring training.

“We were kind of on the fence which way to go,” trainer Stan Conte said. “He won’t be back this year. We’re optimistic for him regaining strength and getting the knee calmed down.”

Benitez was examined on Monday’s off day by 49ers doctor Michael Dillingham, who has experience with arthritis cases. Dillingham recommended rehabilitation rather than an operation to clean up the joint. The 33-year-old Benitez, in his second season with the Giants and 13th in the big leagues, had been scheduled to begin a strength and physical therapy program soon.

Benitez, seventh among active closers with 280 saves, went 4-2 with a 3.52 earned-run average and 17 saves.