David Robertson (foot) has been diagnosed with a bone bruise and will wear a walking boot until Monday. It's good news for the Yankees, as Robertson doesn't have any broken bones and an MRI also came back clean. He will begin to work his way back to action after the boot is removed, and manager Joe Girardi said he "would think" the right-hander would be ready for Opening Day. Robertson, who will turn 27 in a month, will set up again for Mariano Rivera this season after posting a 1.08 ERA and 100/35 K/BB ratio over 66 2/3 innings in 2011.