Phil Hughes’ back is without pain. However, his slider could use an aspirin. Hughes, who remains a question mark to start the season in the rotation, made it through a 27-pitch bullpen session yesterday morning at Steinbrenner Field. “I am pain-free, which is the biggest issue. Now it’s just a matter of getting back in the swing of things,’’ Hughes said following his first full bullpen session since being sidelined early in camp. “I was kind of disappointed with a couple of things, but overall I got through it without any issues and that was a big step.’’ That Hughes could be annoyed with a misbehaving slider is a strong indication the discomfort from a bulging disk in his upper back has been eliminated. “My slider at the end was terrible, but I threw one good one at the end and at least I can end on a good note,’’ Hughes said. Hughes previously threw 10 pitches off a mound Saturday. He said he will throw batting practice Thursday. After that it could be a simulated or exhibition game. As for whether there is enough time for him to return to pitch during the first trip through the Yankees’ rotation, Hughes deferred to pitching coach Larry Rothschild. “That is a question for Larry. I know he has his dates when I have to do certain things by,’’ Hughes said. “I don’t know what they are off the top of my head. He has dates in mind where I have to be in a game by. He would know better than I would, but I don’t think it’s out of the question.’’