FILE: Oakland Athletics v New York Yankees

Yankees starter Masahiro Tanaka pitches in the third inning against the Athletics at Yankee Stadium on June 5. (Jim McIsaac / Getty Images / June 5, 2014)

Japanese pitching sensation Masahiro Tanaka was diagnosed with a partially torn ligament in his right elbow on Thursday.

New York Yankees general manager Brian Cashman said the right-hander visited three doctors and each one confirmed a small ligament tear in Tanaka's ulnar collateral ligament.

Tanaka, who was placed on the disabled list Wednesday, will initially attempt non-surgical intervention that includes a platelet-rich plasma injection before starting a throwing program. The hope is that he can return in about six weeks.

If the rehab fails, Tanaka likely will undergo Tommy John reconstruction surgery that will require at least 12 months of recovery and rehab before he pitches again.

The 25-year-old Tanaka was off to a strong start in his first season with the Yankees after signing a seven-year, $155 million contract during the winter. He posted a 12-4 record with a 2.51 ERA and 135 strikeouts in 18 starts, but he was 1-3 with a 4.25 ERA in his last four outings.

Tanaka's injury is the latest to hit the Yankees' pitching staff, which already lost CC Sabathia and Ivan Nova for the season.