Fall, 23, averaged 7.2 points, 4.0 rebounds, and 1.4 blocked shots in five summer league games, and delighted Celtics fans.
"Tacko is fun to watch. He makes me laugh," Celtics president Danny Ainge told MassLive earlier this month. . "Some of the plays he makes are hilarious because you just don't see them. Guards get in a bind and they just throw the ball up in the air, then Tacko grabs them and makes tip-toe dunks from under the basket. It's just like a senior in high school playing against fourth graders sometimes out there."
ESPN reported on June 21 that Fall would sign with the Celtics on an Exhibit 10 contract, which are one-year deals paying the minimum salary.
Fall is a native of Dakar, Senegal, and he and 76ers star Joel Embiid are part of the delegation the NBA will send to Senegal for the Basketball Without Borders Africa camp next week.
Green, 26, played with Ratiopharm Ulm in Germany, where averaged 13.8 points, 4.7 rebounds, 1.6 assists, and 2.3 steals in 51 total games across both the German BBL.
He played in all five of the Celtics' summer league games, averaging 10.8 points, 4.8 rebounds, 2.8 assists, and 1.8 steals in 22.6 minutes.
The Celtics also signed guards Tremont Waters and Max Strus to two-way contracts.