The Hawks (9-4) trailed by as many as 11 points in the first half and were lucky to be down by just 25-23 at the break as the Pioneers ran one backdoor cut after another past surprised defenders.
"You can talk it, but you have to have a very, very high basketball IQ to be able to assimilate what you see on tape to what you see on the court," Martelli said.
Langston Galloway scored 14 points and DeAndre Bembry 13 for the Hawks. Ronald Roberts had nine points and 15 rebounds.
St. Joe's held Denver to just 10 field goals after halftime and should have walked away with a comfortable win if not for free-throw shooting, which has been an Achilles' heel all season. The Hawks, who entered the game shooting 66.4 percent from the line, made just 56.5 percent (13 for 23) against the Pioneers and missed 4 of 6 on three straight possessions late in the game.
"If somebody has an idea of hypnosis or anything you can think of, I'm in because it can't continue," Martelli said.
The Pioneers (7-8) had two chances to go ahead or tie in the final seconds, but Marcus Byrd missed a three-pointer, and Chris Udofia rimmed out with a follow attempt from close range.
Chris Wilson iced the game with a pair of free throws with 0.6 seconds left that put the Hawks up four. Bryant Rucker hit an unguarded three-pointer at the buzzer for the final result.
The win leaves the Hawks feeling good entering Atlantic Ten play, beginning Wednesday at No. 23 UMass.
"Now it's time to measure up and see where we are," Martelli said. "It's our vehicle, always has been, and always will be, if we really desire to play later in March."