In the minutes after making the selection, Sixers general manager Ed Stefanski explained that the Sixers were so sold on Vucevic that they considered moving up in the draft to secure him.
Vucevic, 20, said he "had an idea" that he would be coming to Philly.
"He was in the mix for us all along," Stefanski said.
Continued Stefanski: "This was a brutal draft. . . . There were surprises all night long. In the draft room, we were shocked at where particular players went. Again, we were just looking to see if Vucevic could fall to us."
Vucevic, 20, played three seasons for the Trojans. He was born in Switzerland, raised in Belgium, and moved to Montenegro with his family as a teenager. His father, Borislav, played professionally overseas for 24 seasons.
"He wanted to come here. His agent told me," Stefanski said. "The kid is in love with [coach] Doug Collins and wants to play for him, so he's going to get his opportunity."
Vucevic said he and Collins had a number of great conversations.
"You could tell in the times we talked that he's a great person," Vucevic said. "I would really fit well with his system. He told me a lot of great things about me, what he liked about me, and which ways he could help me. I felt like it was a great fit for me."
In Vucevic, the Sixers said they are getting a pro-ready big man with solid fundamentals and legitimate NBA size.
Before the draft, the Sixers had only one interior player under absolute contract for next season: reserve Marreese Speights. Last season's starting center, Spencer Hawes, is a restricted free agent, and veteran Tony Battie, who played out his one-year contract last season, is an unrestricted free agent.
Vucevic adds much-needed bulk to the team's interior.
"Because of his basketball IQ and his shooting ability and his passing of the basketball, he will fight for some time as a rotation player," Stefanski said.
During his junior season with USC, Vucevic averaged 17.1 points and 10.3 rebounds a game. He was initially projected as a second-round pick but began climbing the draft charts after a strong showing at the NBA combine in Chicago.
The Sixers interviewed Vucevic at the Chicago combine and also hosted him for a predraft workout at the team's practice facility, the Philadelphia College of Osteopathic Medicine.
"We are incredibly thrilled to draft Nikola Vucevic," Collins said in a statement. "I liked him from the moment I saw him at the Chicago predraft camp. He is a hard working, skilled big man with the desire to succeed who gives us more size in the frontcourt, which is a need. He is a player that we are ecstatic to have on our roster, and I look forward to coaching him."
As for Allen, a Pennsbury High School graduate, he said he was happy to stay close to home "where my family and friends are able to support me."
Allen was the 2011 Big 5 most outstanding player. He ended his career as Temple's all-time rebound leader (1,147) and 24th on the all-time scoring list with 1,421 points.
There were some early-day rumblings that the Sixers might be in discussions with the Minnesota Timberwolves to trade Andre Iguodala, but as the draft neared it became clear that the team would stick with its selection.
Contact staff writer Kate Fagan at email@example.com or @DeepSixer3 on Twitter. Read her blog, "Deep Sixer," at www.philly.com/deepsixer.