 During the combine, he put up new records at the event, including height (which received comparisons to former NBA player Manute Bol), wingspan, and standing reach.Despite going undrafted in the 2019 NBA Draft, Fall was signed to an Exhibit 10 Contract on June 21, 2019 by the Boston Celtics.Fall played for the Celtics during the 2019 NBA Summer League season, scoring six points in his first game alongside four rebounds; in his second game he tallied twelve points for his first double-digit scoring game, alongside another rebound.