LEXINGTON, Kentucky: "I love challenges," Rick Pitino said after announcing he would leave the University of Kentucky to become the new coach of the Boston Celtics. Pitino insisted the money, a reported $70 million over the next ten years that would make him the highest-paid coach in any sport, was not the reason he was departing Lexington. He compared the situation in Boston to that of eight years ago at Kentucky and said he again would again try to "build a program in shambles up to the championship level." In Pitino, the Celtics have landed a marquee name, a local New England hero and master builder who by turns has led Providence College, the New York Knicks, and the Kentucky Wildcats out of their respective basketball basements. The once-dynastic Celtics, 15-67 last year under M.L. Carr, need those talents badly. Pittino's first priority will be to keep Celtics legend Larry Bird in town. Bird, who has repeatedly complained about the lack of decision making among Celtics brass, has been offered a reported $4.5 million per year plus part ownership to coach the Indiana Pacers.