Stephen A. Smith believes the Cavaliers will have a bigger challenge next season if Boston continues to make moves during the offseason. (1:28)

BOSTON -- While the Celtics awaited league approval of their reported swap for the No. 3 pick, the franchise privately worked out 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.

A source familiar with Tatum's solo workout said he impressed with his shot-making and footwork in the drills he participated in.

Boston is also strongly considering Kansas freshman Josh Jackson, sources told ESPN. Celtics general manager Danny Ainge told the Boston Globe that he was trying to get both Jackson and UCLA prospect Lonzo Ball to work out for his team before Thursday's draft.