Kubel, on the disabled list retroactive to May 31 with a sprained left foot, has been taking batting practice with the team but still is dealing with soreness in his foot.
"Jason Kubel is still feeling some discomfort running in the outfield, particularly on lateral movements, and won't be ready to play, so we've ruled him out for San Francisco," Twins trainer Rick McWane said.
Span, on the seven-day disabled list since June 9 with a concussion, has been feeling better but has yet to start baseball activities, so he'll be held out of action against the Giants. McWane, though, said he couldn't give a timetable for how long Span will be out.
"It's really hard to tell," McWane said. "Everybody responds differently to treatment. He's making progress and the test results show that, so that's all we can say for now."
Designated hitter Jim Thome, meanwhile, is close to playing in his first rehab game since going on the DL with a sprained left quad on June 2. He could return to action by next week, but the Twins have an interesting decision to make because they will be without the DH because they're playing in National League parks.
"I would love to have him DH but there is no DH on the next six games on the road," Twins manager Ron Gardenhire said. "So I can't get him ready to DH if there is no DH. So we have to get him back ... we'll see. We'll just see where he's at. I can't tell you how long it's gonna be. So when he's ready and healthy, we'll deem whether he's ready to come back and get [regular] at-bats or just one a game in the National League cities."