CSU (9-22, 4-14 Horizon League) closed to within two with 16 seconds left, but WSU's Mark Alstork calmly knocked down a pair of free throws to close out the game.
The loss ends CSU's bid for the No. 8 seed in next week's Horizon League tournament. Depending on the outcome of Sunday's UIC-Milwaukee game, CSU will open the HL tournament as either the No. 9 or No. 10 seed.
To receive the No. 9 seed, CSU would need Milwaukee to defeat UIC. If that happens, the Vikings would face Green Bay Saturday at noon.
The Vikings struggled to hit shots all game, shooting just 30.4 percent from the field and 7 of 19 from behind the 3-point line.
CSU trailed by as many as 15 with six minutes to go.
A 13-3 run got CSU back into the game. Kenny Carpenter's three-pointer closed the Vikings within 52-47.
Then the Vikings would catch a break as WSU split a pair at the free throw line.
On CSU's next possession, Carpenter had a three-pointer that rattled in-and-out that would have cut the lead down to a one possession game.
"If Kenny's three goes down, you're looking at a whole different game," said Vikings head coach Gary Waters.
CSU would catch another break as WSU's Biggie Minnis (11 points) split a pair at the free throw line.
With 16 seconds left, a four-point play from Rob Edwards closed the Vikings within 53-51, but that was as close as CSU would get.
Alstork drained two free throws for the final score.
CSU's defense held WSU to only three points in the final 2:55, all came from the free throw line. The Raiders made only one of its last five field goals.
The Vikings played again without its second leading scorer Demonte Flannigan who missed his second straight game with a concussion.
"I got to give our kids credit because they never quit. They kept going at it. They kept going at it and they kept going at it," Waters said. "Our biggest problem today was we were without our (second) leading scorer and rebounder. You put him in the game and add his 14 points and we win this game by 10."
Without Flannigan, WSU took advantage of the undersized Vikings inside.
Senior center Michael Karena had his way down low, scoring 12 of his game-high 18 points in the first half as WSU built a 28-22 advantage at the half.
Three times CSU would close to within four early in the second half, but WSU started to take control of the game with a 14-3 run that took a 35-31 lead and pushed it out to a 49-34 advantage.
Cold shooting and turnovers plagued CSU again. During that decisive 14-3 run, CSU turned it over four times and missed five straight shots over a six minute stretch.
"We had 18 turnovers that cost us the game," said Waters. "Every game that we lost we have averaged 17 turnovers a game. Every game that we have won we have averaged eight or nine turnovers a game."
Edwards led the Vikings with 20 points, Carpenter added 13 and Andre Yates nine.
CSU's bench was outscored by a whopping 23-0.