DENVER — Josh Smith bounced back from a rocky start with a 93-yard kickoff return for a touchdown and Colorado beat Colorado State 38-17 tonight in what might have been their last game at Invesco Field.

Many fans surely tuned in expecting to see Smith's nephew, Darrell Scott, the Buffaloes' highly touted freshman tailback who was considered by several scouting services as the best back in the nation last year.

Scott gained 50 yards on a dozen carries and leaped over the pile for a 1-yard TD to cap the scoring in the closing minutes. But this night belonged to his uncle as the speedy sophomore racked up 189 total yards.

The game featured three touchdowns in a 26-second span of the second quarter, including back-to-back kickoff returns for touchdowns by Smith and CSU sophomore John Mosure.

Rams linebacker Jeff Horinek picked off Cody Hawkins' deflected pass at the Colorado 24 and, two plays later, Billy Farris, a senior making his starting debut, hit Dion Morton for a 31-yard touchdown strike that pulled the Rams to 14-7.

Smith, who fumbled away his first kickoff and watched his first punt sail over his head, returned the ensuing kickoff 93 yards untouched for the first score of his career. It was Colorado's first kickoff return for a TD since Jeremy Bloom's 88-yarder at Kansas State in 2003.

Not to be outdone, Mosure answered with a 90-yard TD return in which he broke two tackles around his 20-yard line and sidestepped desperation dive by kicker Jameson Davis as he plunged into the end zone to pull the Rams to 21-14.

That marked Colorado State's first kickoff return for a touchdown since Dexter Wynn did it against Wyoming in 2001.

In a tiff that might subtract rather than add to the biggest college football rivalry in the Rockies, Buffs athletic director Mike Bohn announced Friday that Colorado would exercise its option and move the 2009 game to Folsom Field in Boulder to give the Buffaloes a sixth home game. Colorado State athletic director Paul Kowalczyk responded by moving the 2010 game to Fort Collins.

That means the schools will settle for the respective $650,000 guarantees when they visit their rival instead of the annual payday of about twice that for both schools when they play in Denver.

The ADs have until Oct. 1 to negotiate an extension of the series that dates to 1893 but which included a 25-year dormancy until it was renewed in 1983.

Even if they reach an agreement, it's likely to be a true home-and-home series that bypasses the biggest city in the Rocky Mountains and the largest alumni base for both schools.

The crowd of 69,619 got a good farewell if that's what this was.

This was the only football game — college or pro — televised to a national cable audience from the home of the Denver Broncos and the site just three nights earlier of Barack Obama's historic acceptance of the Democratic presidential nomination in front of about 84,000 people.

The field was torn up in several spots from that event, but play didn't appear to be affected.

Hawkins' second 1-yard keeper into the end zone made it 28-14 early in the third quarter before CSU's Ben DeLine (26) and CU's Aric Goodman (24) traded short field goals.

Then, Smith dived over the pile from a yard out for his first TD in the waning minutes.

The Buffaloes capitalized on a pair of special teams mistakes by the Rams to take a 14-0 lead.

The Rams were controlling the field position until they failed to put enough men on the line of scrimmage for a punt that had backed up the Buffs to their 10-yard line. Smith returned the re-kick to the 42, and five plays later, Scotty McKnight split the defenders on a post pattern for a 35-yard touchdown catch from Hawkins.

On the Rams' next possession, punter Anthony Hartz couldn't handle a high snap and smothered the ball at his 5 as four defenders piled on top. Two plays later, Hawkins' 1-yard keeper made it 14-0.