Had he been healthy, Brooks Lee likely would have debuted and seen plenty of action on the left side of the infield at this point of the season with both Carlos Correa and Royce Lewis nursing injuries. Instead, Lee is dealing with an injury of his own — one that will likely keep him out another month.

Initially called back spasms when he was removed from a spring training game in late March, the Twins revealed Tuesday that the top prospect’s injury has instead been diagnosed as a herniated disk in his back.

“I’d say he’s in the same midrange of what we heard is the return-to-play protocol,” president of baseball operations Derek Falvey said. “He’s almost a month into the first part of the problem. Then, the next month is building back into baseball. So you’re looking at that kind of timeline would be my guess.”

Lee is being treated by specialist Dr. Robert Watkins, and Falvey said he is in the middle of Watkins’ protocol for returning to play.
Lee has started doing very light baseball-type activity, Falvey said, taking light swings.

“With this, you’ve just got to get it taken care of on the front end and then make sure when you’re building him up, you’re building him up pretty slowly,” Falvey said.

It’s tough timing, especially because Lee, the No. 17 prospect in baseball per MLB Pipeline, is coming off an impressive spring at the plate. The Twins have been using a combination of Willi Castro and Kyle Farmer, both off to slow starts, at third base and shortstop with Jose Miranda mixing in at third base.

Rehabbing relievers

Jhoan Duran began a rehab assignment on Tuesday night in St. Paul, and Justin Topa is right on his heels. The two Twins relievers have been on the injured list all season, but both are almost ready to return,

Topa, who was dealing with patellar tendinitis in his left knee, threw around 20 pitches on Tuesday at Target Field. It was his first live batting practice — previously he had thrown two regular bullpens and one with Royce Lewis standing in, tracking pitches.

Next, he plans to head over to St. Paul and begin a rehab assignment Thursday. He expects to throw for the Saints on Sunday, too.

“I kind of lightly penciled in the L.A. series as kind of the goal to be back,” Topa said of the upcoming weekend series in Anaheim. “I think we kind of knew going into it, talking with the doc, talking with (head athletic trainer) Nick (Paparesta) and everybody, that was kind of the plan. Let’s give it some time to calm down for a couple weeks, build up after that, and I think we’re pretty much on track with what we initially thought it was.”

Briefly

— Starter Brent Headrick is on the minor league injured list with a forearm strain, and the Twins recently transferred him to the 60-day injured list in the minors. “It’s just going to take some time to build back up,” Falvey said.

— Matt Canterino, also on the minor league injured list with a shoulder injury, has started throwing between 40-60 feet.