On the day Jared Sullinger received what his teammates considered a snub, when the Celtics rookie was left off the roster for the Rising Stars Challenge for top rookies and second-year players, on All-Star weekend, something far more serious emerged. Sullinger, whose slide in last June's draft was spurred by a history of back trouble, left last night's 99-81 win over Sacramento in the first quarter with back spasms. His status is considered day-to-day, though as Doc Rivers later let on, Sullinger has been fighting spasms for at least a week. "I know Eddie (Lacerte, the trainer) said something a week or two ago that it's been bothering him, and I think this will be what will happen," the C's coach said of the problem. "He'll have these episodes and we've got to get him through it. Hopefully he doesn't miss games with them, but if he does he does. And then get it right and come back. But I'm not sure if it was before the game or not." Sullinger left the locker room without talking. As far as his Rising Stars snub goes, though, the rookie was at least outwardly unaffected. "Not a disappointment," he said. "My focus is the Boston Celtics. I don't worry about individual goals. It would have been nice, but at the same time it gives me a chance to rest up. All of our roles are about to be bigger. It's going to give me time to get ready for the second half of the season. I can rest up and learn." Nor was Rivers bothered. He probably wants as many of his players to get some rest for the post-All-Star break stretch run, too. "Yeah, it's a surprise, and I'm really concerned with all of that stuff," the Celtics coach said with a laugh. "Listen, he'll make it eventually, maybe not (in that game), but he'll be in the league a long time, and he'll be happy with that in the long run."