The Illini (4-0) opened up 23-point lead, 66-43, with 12 mintues left in the game on a jump shot by Nichols. The Thundering Herd (4-2) never threatened again.
The Illini held Marshall leading scorer Jon Elmore to 14 points. Elmore entered the game averaging 28.3 points. He made 2 of 11 shots on the night, including 0 of 5 in the second half.
Jarrod West led Marshall with 22 points.
Mark Smith and Michael Finke added 13 each for Illinois.
The Illini used big advantages in bench scoring and rebounding to close out the Herd. The Illini outrebounded Marshall 45-20 and had 42 points off the bench to the Herd's 10.
Easy win aside, first-year Illinois coach Brad Underwood was clearly frustrated by his team's inconsistencies on both ends of the court.
''What am I seeing? What am I seeing?'' he yelled to the scorer's table after one possession, following that up with an order to his team as they brought the ball back up the court. ''I want to see a good shot down here! I want to see a little toughness!''
Marshall: After falling Thursday to Morehead State, the Thundering Herd have lost two straight. Beyond its starting lineup, Marshall had almost no offensive production Sunday. And if Elmore isn't scoring, the Herd don't have an answer on offense.
Illinois: Bench points were again a big key for Illinois. For a second straight game, Nichols scored in double figures off the bench (he had 16 Friday in a win over DePaul) and Trent Frazier added 10. Underwood, though, picked out both Nichols and Frazier during the game for defensive lapses. ''Trent, you can't be that soft!'' Underwood yelled on one possession midway through the second half. The Illini also started knocking down 3-pointers for the first time this season, making 7 of 15, including 4 of 6 in the second half after entering the game 15 of 65 (23.1 percent).
Marshall ends its two-game road swing, hosting North Carolina Central on Wednesday (Illinois will host the Eagles on Friday).
Illinois will host Augustana, a Division III school from Rock Island, Illinois, on Wednesday.