CHICAGO — Jason Castro's right knee has been sore for a couple of weeks, and it flared up again on Friday. So on Saturday, the Twins decided to place their catcher on the 10-day disabled list to give it a chance to heal itself.

Bobby Wilson, an eight-year major-league veteran, was summoned from Class AAA Rochester, and will be in uniform tonight at Guaranteed Rate Field.

Castro underwent a magnetic resonance imaging test on his knee Saturday morning, and it located a slight tear in the meniscus. The injury isn't serious enough to require surgery, and the Twins don't anticipate Castro needing more than the 10 days off before returning.

"Actually, the defensive side was where I felt it the least, surprisingly," Castro said of the nagging pain. "It's just been something I've been trying to fight through. It's at the point now where I should probably be smarter."

Castro has experienced these slight flare-ups occasionally in the past, always on the right knee, he said, and the pain was beginning to subside. But it returned on Friday during his last at-bat. "I saw him take a check swing, a half swing, and then he stepped out and I could see him kind of grab down there. He tried to bend it, shake it out a couple of times," Twins manager Paul Molitor said. "I checked on him when he came in, and he said he was going to be able to get through the game. We examined him again after, and decided to get the MRI today."

Castro, who will have a cortisone injection in his knee this weekend, might not have needed a full 10 days to return, Molitor said, but he didn't want to play with only one healthy catcher on the roster.

Rookie backup Mitch Garver figures to get most of the playing time in Castro's absence, with Wilson filling in occasionally.

Wilson, a 35-year-old catcher signed last winter to a minor-league contract, was 5-for-40 at Rochester in 11 games. He has played for five other major-league teams, most recently in 2016 with the Rays.

To make room on the 40-man roster, righthander Ervin Santana was moved to the 60-day disabled list, a transaction that means Santana will not be eligible to return to the Twins until May 28. That's only a couple of days longer than he was anticipated to return, if that, Molitor said, because Santana has not yet faced hitters, even in batting practice, as he rehabs his pitching hand after offseason surgery.

"I don't really think it's going to cost us," Molitor said, adding that Santana's return now figures to be around the first week of June.

Santana threw 30 pitches from a mound in Fort Myers on Friday, Molitor said, but only fastballs and changeups. He has thrown his slider on flat ground, but not from a mound.

Romero ready to bat

Fernando Romero made a discovery Friday that came as a bit of a surprise. "Hitting is kind of difficult," the rookie righthander said. "Trying to make contact is hard."

Anyone facing Romero and his 98-miles-per-hour fastball probably agrees, but the revelation occurred to him after the Twins asked him to take batting practice — there was a heavy emphasis on bunting, too, of course — in preparation for his second start, which comes Monday at St. Louis. With no designated hitter, Romero will be asked to hit.

He has never swung a bat in a professional game, and never really tried it much before that, either. "I was always a pitcher. But I'll do it," he said. "I hope I can put the ball in play."

Etc.

• Trevor Hildenberger on serving as eighth-inning setup man, a role he occupied for much of September last year, for Fernando Rodney on Friday: "It was an awesome vote of confidence from Mollie. I know [Addison] Reed had thrown three days in a row, and we needed someone to step up. The fact that he called on me felt really good, and the fact that I was able to get out of it with a zero also felt really good."

• The White Sox put infielder Yoan Moncada on the 10-day disabled list because of tightness in his left hamstring, after he left Friday's game early.