Watson totaled a career-best 32 points to go along with nine rebounds and six assists. Freshman forward Joe Herrmann finished with 30 points and nine boards while senior guard Daryl Moore and junior forward Stephen Laird each added 20, respectively. Freshman guard Gary Gates had a career-high 13 rebounds to go with five assists in the win.
Mark DeMonaco led the Titans with 24 points, seven rebounds and six assists.
Thiel (8-18) ran its lead to as many as 13 (25-12) midway through the first period. The Titans used a 15-6 run over the last 3:50 to trim the Tomcats' lead to just three (56-53) going into the half.
Watson was a perfect seven-of-seven from the field in the opening half for 18 points.
After watching the Titans take a 63-62 lead just 2:09 into the period Thiel responded with a 14-1 run to pull back in front by 12 (76-64) at the 14:15 mark.
DeMonaco's lay up at the 6:33 mark brought Westminster back to within three (94-91) before his three-pointer with just under three minutes opened up a 101-99 lead.
Moore knocked down a jumper with less than a minute to play to put the Tomcats up four (105-101) before Thiel made five-of-six free throws down the stretch in claiming the first-round win.
Thiel finished with a decided 53-40 edge while limiting the Titans to just 38.3 percent from the field.
Thiel will travel to Bethany College to take on the top-seeded Bison on Thursday, Feb. 24. Tip off is scheduled for 7:30 p.m.