It is make or break for the Colorado State men’s basketball when the team takes on Mountain West leader San Diego State on Saturday.

A win could make the difference come tournament selection in March. The Aztecs were preseason favorites to win the conference and currently sit atop the MW at 5-1 in league play.

CSU head coach Larry Eustachy and his players will be quick to tell you that next game is always the biggest, but it is hard to deny that this matchup feels even bigger than others.

“I can sit here and say it is just another game, but human nature becomes involved too,” Eustachy said. “I am sure it is not just another game to our guys.”

And how could it be? Eustachy referred to SDSU as the premier team in the conference. In the last five seasons, they have been the MW regular season champs three times and won the MW tournament twice. To win the conference, you have to go through the Aztecs.

Steve Fisher’s team is led by veterans Winston Shepard (11 points per game, 4.9 rebounds) and J.J. O’Brien. They are without one of their best in Dwayne Polee II, but junior guard Aqeel Quinn has stepped up his scoring in Polee’s absence with 45 points over the last three games.

Only two current CSU players, Joe De Ciman and Daniel Bejarano, were on the team in 2012-2013 when the Rams last defeated the Aztecs, so they know how intense the atmosphere can be in this matchup.

“I think the new guys kind of have a feel for that environment with (the) Wyoming (game),” De Ciman said. “We have to enjoy it. We cannot let it affect us and do things we do not normally do.”

CSU has played in front of some big crowds this year — at Colorado, at New Mexico, and in front of a neutral crowd for the Great Alaska Shootout — but it was not until Wyoming came to visit on Jan. 7 that the Rams experienced that type of noise at home.

Eustachy said afterward that the strong showing by fans may have actually thrown some players off. They had experienced big crowds but not at home. Now that they have had a taste, Eustachy expects it to work to their advantage.

“It was new to a lot of them; now it won’t be new,” Eustachy said. “A racehorse almost always runs a better race the second time it is run than the first.”

It will not be new to Fisher and his team either. They know how to win on the road.

“They love this type of situation,” Eustachy said. “It’s what they are used to.”

CSU started slow against Wyoming. If the Rams come out flat on Saturday, they could find themselves dead in the water. The Aztecs can hold a lead and close out games as well as any team in the nation.

“I remember when I was a freshman and they were 90-0 when they’re leading with five minutes left,” De Ciman said. “Now they are 133-0 when leading with five minutes to go. That is special.”

The ability to finish games is a product of SDSU’s defensive acumen. They specialize at coercing opponents into tough shots and then denying second-chance opportunities.

“They are long and they are intense, and they can gamble and recover because of their rotations,” Eustachy said. “I mean, they are very sound defensively … That is what they have always won with is their defense and their rebounding.”

That intensity often reflects in the box score. SDSU ranks third in the NCAA in scoring defense, surrendering just 52.6 points per game to opponents.

“I know they press a lot and they like to double-team the corners,” junior guard Gian Clavell said.

That aggressiveness can be enough to break some teams. Opponents have been turning the ball over 14.6 times per game against the Aztecs.

Clavell is excited for the matchup but knows that there will be less room for error than usual.

“We need to start on the right foot and get on track,” Clavell said. “Get our practice into the game, don’t even think about it and have fun.”

Eustachy said he felt the team started too slow against Wyoming, which ultimately cost them the game. Starting slow against SDSU is practically a death wish. The Aztecs only loss in MW play this season came at Fresno State, a game which the Bulldogs opened on a 19-3 run. Hitting the ground running will be a key for CSU in front of their home crowd.

“We were not as determined as Wyoming to start the game and that’s a must against San Diego State,” Eustachy said. “Otherwise, we might as well just not go.”

CSU and SDSU are set to tip off at 8 p.m. Saturday at Moby Arena. The game will be broadcast nationally on ESPNU.

Collegian Sports Reporter Emmett McCarthy can be reached by email at emccarthy@collegian.com and on Twitter @emccarthy22.