Michigan big man Mitch McGary, who spurned the NBA after his breakout performance in the NCAA tournament, will miss the Wolverines' season opener because of a lower back injury.

Mitch McGary was named to the AP preseason All-America team after averaging 7.5 points and 6.3 rebounds per game last season as a freshman and helping propel Michigan to the NCAA title game. AP Photo/Tony Ding

"He's improving every day, making great improvements in everything he can do," coach John Beilein told WTKA-AM in Ann Arbor. "No, he won't [be available Friday]."

Michigan opens the season Friday night at home against UMass-Lowell.

The 6-foot-10, 265-pound McGary, named a preseason All-American by The Associated Press, sat out the preseason and the timetable for his return remains uncertain. Sources have told ESPN.com that McGary's health has improved over the past month but that the staff is being cautious in hopes he won't miss a significant portion of the season.

McGary averaged 7.5 points and 6.3 rebounds per game last season as a freshman but was critical for the Wolverines in their run to the national title game. He averaged 14.3 points and 10.8 rebounds in the six tournament games and would have been a likely first-round pick in the NBA draft.