Avdija landed awkwardly after having a layup late in the second quarter against the visiting Golden State Warriors and has been shot off the courtroom in a wheelchair.
Avdija underwent X-rays on the ankle that revealed the hairline fracture, which will not need surgery and has a recovery time of two to three months, the source told Wojnarowski. An MRI is set for Thursday to test for ligament damage.
Avdija lay on the floor for many minutes following the injury, as teammates coated his lower right leg using a set of warm-up pants in the seat as the coaching staff arrived.
"Seeing a guy go down like that is real scary," Wizards heart Daniel Gafford said. "You will never understand what's going to happen. Seeing him down to the floor as long as that, I felt his pain. I understand it is likely to be a very long road to recovery, but with the coaches that we got, he's in great hands.
"It is a hard blow for him right now, since I'm pretty sure he is going to be out for a good amount of time. It's real hard. A foot injury is one of the worst harms, to me, because I've been through that."
Washington picked Avdija, 20out of his native Israel together with the ninth pick in last year's NBA draft.
"Two things about Deni I adore: He also cares a lot and he works really hard," Wizards coach Scott Brooks said. "And people are two attributes that we want our program to be about. Has he had an up-and-down year, absolutely. You look at all the great rookies, the MVPs from the league, examine their rookie year, it's not any different. From time to time, we place too much pressure on these players to be 27-year-olds right away.
"Deni cares, he works hard, is an outstanding child and we are lucky to have him on our team. We will keep getting him better."
The Wizards already are without beginning center Thomas Bryant, who is out for the season with a torn left ACL. And forward Rui Hachimura did not play Wednesday because of left knee soreness.
All-Star guard Bradley Beal rallied Washington from the fourth quarter because of its season-best sixth straight victory, 118-114, from the first Wizards home game with enthusiasts in more than a year. Beal, who has suffered his share of leg injuries during his career, said that he talked to Avdija following the game and that the rookie was in great spirits.
"My advice would be the same I would give myself if I was a rookie," Beal said of handling a long-term injury. "Just understanding your own body is increasing, there will be some ups and downs, there is going to be a lot of things you can't control.
"Just staying positive, knowing that you are able to return on the other side of the a better player and even more powerful."