"We're hoping there's nothing significant," Twins manager Paul Molitor said. "We're going to get him checked out by our people and then get him in a situation where we can get him some isolated treatment with our rehab trainers back there over the weekend and see if he responds and gets back to action when we get back for the homestand."
Sano said he woke up with back pain about 10 days ago and that it progressively got worse. He said it also hasn't felt any better since he left Monday's game.
"I'm not really sure what's wrong with my back," Sano said. "With God's help, I hope I can play again and finish strong this year."
Sano said it's the second time in his career he's had a back injury, as he also had back pain for two months in 2009 after signing with the Twins. But he's hopeful this injury isn't as serious, and he said he doesn't believe the extra work he puts in at third base before games contributed to the issue.
"It's something where I woke up one morning and I felt it," Sano said. "I don't think it has anything to do with early work."
Sano, who has several friends and family members in New York and plans to live there in the offseason, said he was disappointed to miss the series. Molitor remains optimistic he could return before the season ends, but the team will be careful.
"It's risk-reward," Molitor said. "You'd like to see him play as much as he can, but you don't want to risk too highly the possibility of things progressing in the wrong direction."
• After missing four games with sore quads, Joe Mauer returned to the lineup as the designated hitter against the Tigers on Thursday. Molitor said he's hopeful Mauer will be available to play this weekend against the Mets.
• Catcher Kurt Suzuki, who received five stitches in his chin after being hit on the facemask from a foul ball on Wednesday, was held out of the lineup on Thursday. The Twins don't have the luxury of having a designated hitter against the Mets, which could delay Suzuki's return. He's available to hit, but Molitor said they will have to weigh the risks of reopening the cut before he returns to catching.
• Double-A Chattanooga manager Doug Mientkiewicz is set to the join the coaching staff on Friday, and he will remain with the club until the last series of the season. Mientkiewicz will miss the final series to attend the final regular-season games of David Ortiz's career, as the two were teammates on the Twins and Red Sox.