Walkup was 10 of 12 from the field with seven rebounds and six assists for the Lumberjacks (14-5, 7-0 Southland). Demetrious Floyd was 8 of 11 with four 3-pointers for 20 points, Ty Charles had 13 points and Clide Geffrard added 11. Stephen F. Austin shot over 62 percent.
Lamar (10-10, 2-6) was led by Nick Garth with 12 points. The Cardinals were 2 of 16 from beyond the arc, made just 10 of 20 free throws and committed 22 turnovers.
Stephen F. Austin took control early with a 12-0 run - including a 3-pointer and layup by Floyd - to go up 18-6. The lead went over 20 on C.J. Williams' layup with 4:33 in the half, and the Lumberjacks led 45-20 at intermission.
SFA started the second half with a 12-2 run over the first 3 1/2 minutes, and cruised from there.