Mike Hampton's struggle to return to the Atlanta Braves' rotation suffered another setback on Sunday when he felt pain in his left elbow and had to stop throwing in the bullpen. Hampton strained an oblique muscle last month, and that pain in his left side kept him from pitching in a game during spring training. But the recurrence of soreness in the elbow could be a greater concern. Hampton missed the 2006 season following reconstructive surgery on his left elbow, and he felt more pain in the elbow Sunday.