The ticket sold in Onondaga County, N.Y., was the only one to match all winning numbers from Friday night's drawing.
The next Mega Millions drawing, Tuesday night, will feature a grand prize of $12 million.
In addition to the grand prize winner, four players won second prizes of $250,000 apiece. None of those tickets were sold in Illinois. Another 21, players, including two from Illinois, won third prizes of $10,000 apiece.
The winning numbers from Friday night's drawing were: 23, 30, 36, 39, and 48. The Mega Ball number was 34.