BOSTON --? Celtics?guard Kyrie Irving will sit out Thursday's visit from the Philadelphia 76ers with a sore left shoulder but said an MRI revealed no structural damage, and he hopes to return to action as early as this weekend. Irving said he has battled increasing soreness in his shoulder in recent weeks and is sitting out Thursday's game as a precaution. Irving said he could be back on the floor for Sunday's game against the Magic. Marcus Smart starts in Irving's place Thursday against the Sixers. "Just precautionary stuff and just making sure everything is all right from a strength perspective," Irving said before Thursday's game. "Obviously a few days will definitely put me where I need to be, and we'll just see what goes on for Sunday's game. It's nothing too crazy. It was just giving me a little discomfort over the past few weeks, and I've just been playing through it, in terms of preparing best for every single game, and I just felt it best to get a...