OAKLAND -- Twins third baseman Miguel Sano, who returned to the lineup on Tuesday after missing 12 games with a left knee injury, flew back to the Twin Cities for further testing on his knee, manager Paul Molitor said Friday.
Sano suffered the injury on a slide in Houston on Sept. 4, getting carted off the field after jamming his knee into the second-base bag. There were initial fears it could be a significant injury, as he had a titanium rod inserted in his left shin in the offseason. But he felt good enough to return to the lineup on Tuesday, only to feel discomfort in the back of his knee while playing.
"It seems to me it was more like he was getting a nerve-jolt sensation at times," Molitor said. "So we sent him back for more testing to try to find the source of that. It wasn't reaggravated by playing the other day. It's just kind of persisting. He tried to play through it but after the game we decided to find the answer to that."
Molitor said he hasn't received any test results yet and there's no timetable for Sano's return. Sano, 25, went 0-for-4 with four strikeouts on Tuesday, and is hitting .199/.281/.398 with 13 homers, 14 doubles and 41 RBIs in 71 games this season.
Sano was an All-Star in 2017, but has struggled this year after his shin surgery in the offseason. He was sent to the Minor Leagues for a six-week stint from mid-June until late July to work on his conditioning, but has hit .195/.294/.390 with six homers and 14 RBIs in 34 games since returning.
Worth noting
• Left fielder Eddie Rosario underwent an MRI exam on his strained right quad, which revealed inflammation. He's expected to miss the rest of the season but Molitor said they'll find out more on Tuesday, when the Twins return home to Target Field.
"No surprises," Molitor said. "Just kind of confirmed the inflammation in that right quad. It's still listed as mild to moderate in that right quad. So no real new information on that."
• Catcher Mitch Garver is also not expected to catch again this season after suffering a concussion on Sept. 12, but there's a remote chance he could return as a designated hitter next week.
"Garver's doing better," Molitor said. "Still think the catching is not going to happen, but we'll have to decide on the worthwhile efforts of trying to get him at-bats or not when we get home as well." 
• Second baseman John Forsythe woke up with inflammation in his right knee on Friday and was held out of the lineup. It's not considered serious, but the Twins wanted to be cautious on Friday.
"He doesn't really know how or why," Molitor said. "The hills of San Francisco are our best guess."
• Reliever Addison Reed will be away from the team for a few days, as his wife, Cady, is due any day with the couple's second child.