Sam Houston (8-13, 2-5) led only once in the first minute but fought back from 19 points down to cut the Roadrunner margin to just nine points, 73-64 with 2:20 to play.
Melvin Johnson was one of five players in double figures for UTSA (14-7, 6-1), scoring 18 points. Alex Vouyoukas scored 14 points and Kannon Burrage added 13 for the Roadrunners.
Konnor Tucker scored 17 points and Marcus James and Demarcus Gatlin each added eight points. The Bearkats outscored UTSA 34-20 in the paint, out-rebounding UTSA 40-23. Werner pulled down nine rebounds and James totaled six boards.
The Roadrunner defense turned 22 Bearkat turnovers into 22 points. Both teams shot well from the field, UTSA hitting 23-of-53 (43.4 percent) and Sam Houston 23-of-51 (45.1 percent).
UTSA held a 24 to 16 edge at the free throw line.
Sam Houston State returns to Bernard G. Johnson Coliseum to play host to McNeese State Wednesday at 7 p.m.