Wildcats spokesman Mike Sheridan confirmed the injury to ESPN.com.
"We're disappointed for Dylan because we know how excited he was about being out there with his teammates," stated Villanova head coach Jay Wright. "But we know that Dylan will work hard during this time so that he is ready to help us as soon as his injury has healed."
The 6-foot-2 Ennis, the older brother of Syracuse freshman Tyler Ennis, averaged 8.5 points, 4.3 rebounds and 4.1 assists per game at Rice as a freshman in 2011-12.
Villanova's Jay Wright said Ennis will figure into the rotation this season with his ability to score the ball on the perimeter. The Wildcats were 20-14 overall last season and return four starters from a team that went to the NCAA tournament.