Guerrero shot 6-of-12 from the field and knocked down three 3-pointers for Fresno State (18-16), which will take on Princeton in the quarterfinals. Marvelle Harris added 14 points for the visitors.
For UTEP (23-11), John Bohannon poured in 18 points, Julian Washburn scored 16 and Vince Hunter collected 10 rebounds.
Neither team shot greater than 36 percent from the field in the first half, but UTEP knocked down all eight of its free-throw attempts and took a 27-26 lead into the break.
The second half was a back-and-forth affair until, with the game tied at 52 with 3:12 remaining, the Bulldogs went ahead for good on a pair of Harris free throws, and they used a 5-0 surge later in the frame to put the game on ice.
Fresno State outscored UTEP from 3-point range, 24-9.