Thatcher has been out for a week with right knee tendinitis. Padres manager Bud Black said no groundbreaking progress has been made, but the reliever has continued to take strides toward a recovery.
"He's getting better," Black said. "He's still getting treatment every day from our trainers, but he is feeling better. We are concerned, like we are about all our players."
Thatcher, who is on the 15-day disabled list, is 0-2 with a 4.50 ERA in 40 appearances this season.
Black said there is no timetable for Thatcher's return, but hopes to have the righty back within the next two weeks.
"Hopefully this turns around within the next week to 10 days and he can get back on the mound," Black said.