Another last-place finish in the Pac-12 South leaves Colorado with plenty to prove as it opens a new season against in-state rival Colorado State.

The wheels fell off for the Buffaloes after a 3-0 start last season. They won just two games in Pac-12 play and missed out on a bowl game a year after winning the school's first Pac-12 South title. It could be an uphill climb again this season. Colorado is replacing its three top receivers and top running back on offense and is trying to bolster a defense that ranked in the bottom third in the Pac-12 in nearly every category last season.

For the Rams, a clash with the Buffaloes offers a chance to bounce back from an unexpected home loss to Hawaii last week. Colorado State (0-1) fell behind by 30 points in the third quarter and couldn't quite erase the deficit in a 43-34 defeat. The Rams gave up 617 total yards to the Rainbow Warriors, raising questions about whether their defense has improved at all from last season.

Colorado holds a 65-22-2 lead in the Rocky Mountain Showdown. The Buffaloes have won three straight in the rivalry series, including last year's 17-3 win in Denver. Colorado State hasn't dropped four in a row to Colorado since losing eight straight to the Buffaloes from 1987 to 1998.

Colorado vs. Colorado State

Kickoff: Friday, Aug. 31 at 9:30 p.m. ET

Where: Broncos Stadium at Mile High (Denver)

TV: CBSSN

Spread: Colorado State -7.5

Three Things to Watch

1. How will Travon McMillian fare in his debut?

Replacing a running back as good as Phillip Lindsay seems like an insurmountable task. Lindsay set school records and gave Colorado's offense a true playmaking threat in the backfield. Fortunately for the Buffaloes, Virginia Tech graduate transfer Travon McMillian should make the transition from Lindsay a smoother one.

McMillian comes to Boulder after rushing for 2,153 yards during three seasons at Virginia Tech. His most productive campaign came as a freshman, when he totaled 1,043 yards and seven touchdowns for the Hokies. He's a bruiser (6-0, 210) and a workhorse type of power running back who will take some pressure off of quarterback Steven Montez and the passing game. McMillian is listed as the co-starter at running back alongside senior Kyle Evans, but it may just be matter of time before the newcomer leads Colorado's backfield.

Another key for the offense is Montez' development. If the junior can take a step forward, that should make things easier for McMillian and Evans to do their jobs. Montez threw for 2,975 yards and 18 touchdowns in 2017, but poor decision making and struggles to read defenses caused Colorado problems in close games last season.

2. Is K.J. Carta-Samuels the real deal?

The performance of Carta-Samuels offered a bright spot for Colorado State in the loss to Hawaii. The senior quarterback roared to life in the second half and threw for 537 yards and five touchdowns as he helped the Rams cut a 30-point deficit to six late in the fourth quarter.

Carta-Samuels set a school record for single-game passing yardage in his Colorado State debut. It also marked the second-most passing yards by a Mountain West Conference quarterback in a game in the 20-year history of the league. His outing helped the Rams amass 653 total yards — their most since 2014 and the fifth-highest single-game total in school history.

In three seasons at Washington, Carta-Samuels totaled just 310 yards and three touchdowns in mop-up duty behind Jake Browning. Given the keys to run an offense, the graduate transfer offers a definite area of concern for Colorado's defense.

3. Which defense will take a step forward?

One common trait shared by Colorado and Colorado State last season was both teams' inability to stop opponents from piling up yards and points at will. It served as an ironic counterpoint to the low-scoring defensive battle the two teams engaged in early in the season.

Colorado's inability to stop the run caused major issues for the Buffaloes last fall. They ranked 109th among FBS teams in rushing defense, allowing 208.0 yards per game. They gave up 450.6 total yards per contest, ranking 110th nationally.

Colorado State struggled primarily with defending the pass. The Rams allowed 244.5 passing yards per game a year ago, which ranked 97th nationally. That pass defense didn't show much improvement in the loss to Hawaii. Rainbow Warriors quarterback Cole McDonald picked apart Colorado State's secondary to the tune of 418 yards and three touchdowns.

Final Analysis

Both Colorado and Colorado State are desperate to show that they have improved from the mediocre product they put on the field a year ago. The Rams didn't start off on the right foot against Hawaii. But their offense does seem legitimately explosive this season. Colorado still has some things to sort out on both sides of the ball. This could be a high-scoring affair that ultimately favors Colorado State.

Prediction: Colorado State 31, Colorado 27

— Written by John Coon, who is part of the Athlon Contributor Network. Coon has more than a decade of experience covering sports for different publications and outlets, including The Associated Press, Salt Lake Tribune, ESPN, Deseret News, MaxPreps, Yahoo! Sports and many others. Follow him on Twitter @johncoonsports.