While the Celtics awaited league approval of their reported swap for the No. 3 pick, the franchise evaluated a new prospect for the first time: Jayson Tatum, according to a source. A league source told ESPN that Tatum -- a 6-foot-8 forward who averaged 16.8 points, 7.3 rebounds, 1.3 steals and 1.1 blocks per game in his lone season at Duke -- worked out for the Celtics at their practice facility in Waltham, Massachusetts. The franchise continues to hone in on who it will select following a trade with Philadelphia that sends the No. 1 pick to the 76ers for the No. 3 selection plus a future first-rounder. That trade was made official Monday afternoon. Boston previously saw Tatum work out in Los Angeles, but Monday was the first time Tatum visited the Celtics.