Lucas competed for the first time since suffering a ruptured Achilles tendon in March. Durrell Summers added 17 points, making 3-of-4 attempts from 3-point range.
The Spartans opened their quest for a third straight trip to the Final Four. They lost in the national semifinals last season to Butler.
Eastern Michigan was paced by Brandon Bowdry with 32 points.
Michigan State held the Eagles to 31 percent shooting and outrebounded them by 12.