ATLANTA — Ray Allen hit two 3-pointers in Boston's 13-0 run in the fourth quarter and protected the lead with two free throws in the final seconds as the Boston Celtics held on to beat the Atlanta Hawks 79-76 on Monday night. The Celtics led 73-58 at the end of the run. Joe Johnson, who had 25 points, had three late 3-pointers as the Hawks rallied.