Haas fell hard on his arm midway through the second half of a 74-48 win. Haas appeared to be in pain after the fall but returned to play several minutes.
Postgame X-rays revealed a fracture in the elbow that will require surgery. The 7-foot-2 center collected nine points and 10 rebounds in the first-round win.
"My whole body hit kind of awkward," he said. "I just laid there for a second. When I rolled over, that's when I felt my elbow."
When speaking to reporters after Friday's game, Haas and coach Matt Painter said they were hopeful that Haas would be healthy enough to continue playing in the tournament.
"I don't know if he hurt his elbow or his wrist or what he hurt," Painter told ESPN before talking to Haas after the game finished. "But this is it for our seniors, so if he can go, I expect he'll be out there giving 100 percent."
Painter later explained what happened when he took the podium after the win.
"I have no idea. He obviously fell on it and he hurt it," the coach said. "So then he was going back. He kept holding it. I don't know if it was his elbow or his wrist, I don't know exactly what it was. But he kept holding it, and that's the reason I took him out there at the end of the game."
Haas averaged 14.9 points per game and 5.6 rebounds per game during his senior season. At times, he served as a focal point for the Boilermakers' offense.
The Boilermakers now face Butler, which defeated Arkansas, 79-62, on Sunday. Bulldogs coach LaVall Jordan said he hated to see Haas' season end prematurely.
"First of all your heart goes out to Isaac and his family and Purdue and Matt [Painter] and that program," Jordan said. "You hate that for anybody. You really hate it for a senior.
"I don't know that it changes our mindset. Purdue is really good and they're not going to put four guys out there. They've got other good players. Obviously their offense through the post changes a bit, but we've got to be ready to guard them. They're a good team. We'll prepare and get ready to go on Sunday."
The Boilermakers' odds to win the tourney went from 12-1 to 25-1 after the Haas news was announced, according to the Westgate Sportsbook.