The Yankees sent Robertson for a battery of four exams on Thursday at a Tampa hospital, making two separate trips. X-rays, an MRI, a CT scan and weight-bearing X-rays all confirmed a diagnosis that Girardi called "as good as it gets for us."
"When they tell you there's a cause for concern, you're thinking there could be something broken, or who knows what it could have been?" Girardi said. "I saw him walk out [on Thursday]; I wasn't real encouraged when I saw him walking."
Robertson hobbled into the Yankees' clubhouse at George M. Steinbrenner Field on Friday with the use of crutches and seemed in positive spirits, saying that he was catching more grief about how he suffered the injury than anything else.
"It's embarrassing; I don't even want to have to come talk to you guys about it," Robertson said, laughing. "I'd rather be like, 'I tripped over a chair in the clubhouse' or something than tell you I fell down those stairs in my house -- and not a full flight of stairs, just, like, one stair."
Robertson said that he was able to sleep better on Thursday and that there had been no swelling, which he took as a positive. He has been taking painkillers since the tumble.
"I'm hoping it's just something that's going to pass in a week or so, and I'll be right back out there," Robertson said. "For the first ... couple of days, it's pretty tough when it's on your foot, because you're walking on it. You feel it so much every step."
Robertson, who will turn 26 next month, was 4-0 with a 1.08 ERA in a team-leading 70 relief appearances for New York last season. Envisioned as the Yankees' eighth-inning bridge to closer Mariano Rivera again this year, Robertson led all American League relievers with 100 strikeouts in 66 2/3 innings.
Girardi said that Robertson, who had made one appearance this spring, could keep his arm in shape by tossing from a chair until he is pain-free and ready to resume working in Grapefruit League action.
"It's tough for me to sit still," Robertson said. "You guys know I can't stop moving."