Jeff Goodman of WEEI.com and FoxSports.com has learned from a source familiar with the situation that Celtics  general manager Danny Ainge was first to contact free agent forward David Lee  once the NBA free agency began after midnight Wednesday night. The 6-foot-9 Lee, 27, played in all 81 regular season games for the New York Knicks  last season, averaging 20.2 points and 11.7 rebounds per game. It was Lee’s best season, having averaged 13 points and 9.6 rebounds per contest throughout his five-year pro career. He has played in 81 games in each of the last three seasons. For more see the Celtics team page by going to weei.com/celtics.