Lawrence (8-3, 3-2 MWC) also got 17 points from Brendan Falls and 13 from Dan Evans. Chris Braier was limited to nine points and five rebounds.
Jason Maclin led Knox (7-6, 3-3) and all scorers with 28 points, and Nick Reineck added 15.
The game was similar to Lawrence's win over Illinois College on Friday. The Vikings again built a sizeable lead but saw the opponent make a late run.
Lawrence built an 18-point advantage on Falls' two free throws with 5:30 remaining. Knox scored the next eight points before MacGillis hit two free throws for Lawrence to make the score 76-64.
Knox kept coming and Reineck hit a 3-pointer to cut the lead to 78-72 with 1:54 left. It was as close as they would get. Lawrence hit just enough free throws (8 of 12) in the final 1:39 to seal the victory.