DETROIT — The Detroit Tigers have placed left-handed pitcher Nate Robertson on the 15-day disabled list with what they're calling "a mass" in his left elbow.

The team announced the move Sunday, retroactive to June 27.

To take his place on the roster, the Tigers purchased the contract of left-hander Fu-Te Ni from Triple-A Toledo. He was 3-0 with a 2.60 ERA there, with 32 strikeouts in 24 appearances.

Robertson is 1-0 with a 7.71 ERA with the Tigers this season.