Medina (elbow) underwent successful Tommy John surgery Wednesday in Arlington, Texas, Jason Burke of SI.com reports.

The Athletics transferred Medina (elbow) to the 60-day injured list Friday.

Medina (elbow) will seek a second opinion on the UCL damage that's sidelined him since July 13, the Associated Press reports.

Medina, who was placed on the injured list Saturday with a right elbow sprain, is expected to miss "significant time" according to manager Mark Kotsay, MLB.com reports.

The Athletics placed Medina on the 15-day injured list Saturday with a right elbow sprain.

Medina allowed one run on four hits and three walks while striking out five over six innings Sunday against the Diamondbacks. He did not factor into the decision.

Medina (0-2) took the loss against Minnesota on Thursday, allowing four runs on eight hits and one walk while striking out three batters over five innings.

Medina (knee) was activated from the 60-day injured list and will start Sunday's game against Atlanta.

Medina (knee) is slated to start Sunday's series finale with Atlanta, Martin Gallegos of MLB.com reports.

Medina (knee) returned to the Athletics following his latest rehab start with Triple-A Las Vegas on Tuesday and could be activated during this weekend's series with Atlanta, MLB.com reports.