He sprained a foot when he stumbled on stairs while moving empty boxes at his home, and the team sounded worried there might be a significant injury to the All-Star reliever. Instead of making his second spring training appearance, Robertson made two trips to a hospital for X-rays, an MRI and CT scan.
"The initial tests that he took gave us some cause for concern," manager Joe Girardi said after Thursday's 6-1 loss to Toronto. "We're not sure what's going on."
Girardi said earlier the initial diagnosis was a mid-foot sprain. Test results will be sent to New York to be evaluated by team physician Dr. Christopher Ahmad. The Yankees said Ahmad will consult with Dr. Justin Greisberg, whose specialties include orthopedic surgery and foot trauma
Between hospital trips, Robertson returned to the clubhouse at Steinbrenner Field and hoped for the best.
"It's embarrassing. I already had Mo rag me out about it," he said after speaking with closer Mariano Rivera.
Girardi emphasized several times the extent of the injury was not clear.
"I'm not so sure that he's going to miss enough time that we won't have him opening day," he said. "I mean until we get the test results, I'm not going to know."
Robertson was hurt Wednesday night at his home in St. Petersburg. He picked up two empty boxes, one inside the other, and walked down the stairs to leave them for recycling.
"I just misjudged one step and just caught it funny, and it just kind of rolled under me," he said.
He understands some may think there's more to the story, that the injury couldn't be caused by a tumble at home.
"I can tell you right now that's the truth," he said. "My wife was like, `What are you doing down there?' She saw me laying there on my foot."
Robertson said his foot started throbbing an hour or two later but he applied ice and it felt better in the morning. Girardi said if Robertson were sidelined for two weeks or less, he still could be ready for the Yankees' opener at Tampa Bay on April 6.
"If it's going to happen, let it happen now," Girardi said.
Robertson had a breakout season in 2011, going 4-0 with a 1.08 ERA in 70 games and becoming the Yankees' primary setup man.
"Last year, he did a tremendous job," Rivera said. "So we're expecting something good out of him this year, also."
If Robertson isn't ready for opening day, Rafael Soriano likely would move up to New York's eighth-inning pitcher.
New York has bad memories of pitchers and injured feet. Chien-Ming Wang sprained the Lisfranc ligament in his right foot while running the bases at Houston on June 15, 2008, and missed the rest of the season. Wang struggled to a 1-6 record with a 9.64 ERA when he returned the following year. He needed shoulder surgery that sidelined him until last July, when he came back to the majors with the Washington Nationals.
"I think he had problems with the shoulder before that," Girardi said.
For now, the sunny optimism of spring training dissipated and was replaced by angst.
"There's always something in every camp," Girardi said. "Something freaky happens, whether it's a foul ball, or you get hit with a ball in BP. It's the nature of the game. It's life. You can't stop living because you have a job. You have responsibilities."
He joked about the need for additional team rules.
"You're not allowed to carry boxes. Kick them down the stairs," he said before pausing and adding: "If he had like an elevator in his house, his arm would have got stuck or something. Just throw them out the window. And hopefully it doesn't land on your car."
Notes: Rivera threw 32 pitches in his second batting practice session. He likely will make his exhibition debut Sunday.