BOSTON -- Celtics guard Marcus Smart engaged in shooting drills Sunday for the first time since undergoing thumb surgery last month and said he could return to action as early as the end of the first-round series against the Milwaukee Bucks. Smart, wearing a new splint on his shooting hand, got up shots before Game 1 between the Celtics and Bucks, then expressed optimism about getting back on the court to help his injury-ravaged team should it hang around in the playoffs. "Today was the first day with the new splint on to actually get out here and do something. So the thumb felt well," said Smart, who underwent surgery to repair a torn ulnar collateral ligament on March 16. "We're on track for [a return in the] next three weeks, possibly Game 7 of the first round, [but] definitely second round. So we're on the right path." Smart injured himself diving to the floor to corral a loose ball against the Indiana Pacers on March 11. It was the same night...