Jump shooting was the key, as the Prairie Fire shot 54.2 percent on 3pointers (13-24), while Lawrence hit on only 7 of 24 (29.2 percent) from beyond the arc.
Jason Maclin led Knox (12-7, 8-4 MWC) with 20 points and Nick Reineck added 18.
Chris Braier scored 16 points and pulled down eight rebounds to lead Lawrence, which fell to 14-4 overall and 9-3 in the conference. The Vikings now lead the league by a game over Knox and Ripon College.
Brendan Falls added 13 points and Dan Evans had 12 points and a game-high five assists for Lawrence.
Knox jumped out to a 10-point lead at the half and increased that to 16 at 52-36 with 15:41 left in the game.
Lawrence scored the next 16 points to tie the game at 52-52. Kyle MacGillis scored five points and Evans and Braier had four points apiece during the run.
Knox came back and build the lead back to seven points. Lawrence got the lead back to five points three times, the last on Evans' jumper with 1:17 left to trim the margin to 70-65.
Jason Harper followed with a layup for Knox and that sealed the win.
Lawrence is at Illinois College on Saturday.