Colorado Springs, CO (SportsNetwork.com) - Will Conant booted a 39-yard field goal as time expired and Air Force played spoiler with a 27-24 win over 21st- ranked Colorado State on Friday.

Colorado State faced a 3rd-and-2 from the Air Force 42 with under a minute remaining when Jasen Oden Jr. was stopped for no gain. The Rams gambled on fourth down, but Dee Hart was also stood up and the Falcons took over with 38 seconds to play.

On 3rd-and-4 of the ensuing possession, Nate Romine fired to Garrett Brown for 26 yards, setting up Conant's game-winner.

Romine, who made his first start of the season, was only asked to throw 15 times for the run-heavy Falcons (9-3, 5-3 MW). He completed just six passes for 135 yards while racking up a team-high 61 yards and a touchdown on the ground.

D.J. Johnson and Shayne Davern also scored on the ground for Air Force, which finished the regular season with a 6-0 record at Falcon Stadium.

The loss overshadowed another big game for CSU receiver Rashard Higgins, who led the nation in yards heading into this week. Higgins made a career-high 12 receptions for 193 yards and a pair of scores.

Garrett Grayson threw for 366 yards, three touchdowns and an interception for the Rams (10-2, 6-2), who had won nine straight. Their loss opens the door for the winner of Saturday's matchup between Boise State and Utah State to advance to the Mountain West title game.

"They beat us on both sides of the ball up front. There were some busted routes but they're the ones that beat us," Colorado State coach Jim McElwain said.

Grayson found Higgins for 22 yards on the second play of the game, then went to him on 3rd-and-9 and extended Colorado State's drive with an 11-yard pickup. On the very next play, Higgins caught a 31-yard pass down the left sideline.

Grayson and Higgins put the stamp on a dominant first drive with a 7-yard touchdown connection. The dynamic sophomore made four catches for 71 yards on the 9-play scoring drive.

Jalen Robinette's 47-yard catch on the first Air Force series led to Johnson's 5-yard TD run to tie the game at 7.

Jared Roberts kicked a 30-yard field goal to cap CSU's next series, but Air Force scored 10 straight points before halftime.

A 12-play series that spanned the first and second quarters culminated with a 1-yard Davern TD run, and Conant was pure with a 33-yard field goal later in the half to send the Falcons into the break with a 17-10 lead.

Romine's QB keeper with 3:09 left in the third quarter put the Falcons up by two touchdowns.

Late in the third, Grayson scrambled on third down and found Xavier Williams near the sticks in traffic and the redshirt freshman did the rest, turning on the jets and outrunning the entire Air Force secondary for a 76- yard touchdown.

After Romine was sacked on third down and Air Force punted, CSU marched down the field in seven plays. On 3rd-and-goal from the 2, Grayson lofted a fade to Higgins in the back right corner of the end zone, and Higgins made a diving catch to tie the game.

Grayson was picked off by Weston Steelhammer on CSU's next drive.

"(We) had some good forward runs and we came up with two big ones, not only the interception, but the big fourth down stop there inside a minute left," Air Force coach Troy Calhoun said.

Game Notes

Steelhammer has an interception in three straight games ... Air Force has won five of six overall ... The Falcons have won nine of 10 in the series ... Air Force ran for 242 yards as a team ... Hart had 115 yards but was kept out of the end zone. He had five rushing touchdowns and a receiving TD last week against New Mexico.