Even with the electrifying return of star receiver A.J. Green, the Bulldogs dropped their fourth consecutive game.
With Georgia driving for the go-ahead score, running back Caleb King fumbled on first down at the Colorado 27 when trying to make a spin move and the Buffaloes recovered at the 30 with 1:55 remaining.
Georgia never got the ball back and Colorado celebrated a 29-27 victory, along with thousands of fans from a crowd of 52,855 in Folsom Field who rushed the field and joined the players.
"That's as basic as a play as we've got," Georgia coach Mark Richt said.
"You say, 'What's our No. 1 running play?' That was it, we just didn't execute it well. They got penetration (from linebacker B.J. Beatty), which was obvious, and then we've still got be able to secure that ball, even if it's a four- or five-yard loss. We've still got to do that and hold onto it, but we didn't. They made a play when they absolutely had to have a play."
Green, returning from a four-game NCAA suspension for selling a jersey to someone classified as an agent, had seven catches for 119 yards and two touchdowns and rushed once for 40 yards.
Colorado (3-1) couldn't stop Green, but cramps could. Green went to the Georgia locker room in the third quarter after the Bulldogs pulled ahead 24-14 and didn't return until the second play of the fourth quarter after Colorado had pulled ahead 29-24.
Colorado, coming off four consecutive losing seasons - including 3-9 in 2009 - added to the Bullldogs' season of misery.
"There's going to be frustration," defensive end Demarcus Dobbs said. "We're Georgia. We never expect ourselves to get four losses or lose to the teams we have lost to. We just have to push ahead and we cannot give up on each other. All we have is each other."
Green's return turned out to be no panacea for the faltering Bulldogs, even on a night where he made touchdown catches of 3 and 39 yards.
Georgia's longest losing streak in 20 years stretched to four games even though it outgained Colorado 409 yards to 393.
The Bulldogs (1-4) need a win Saturday at home against Tennessee to avoid its first-five game losing streak in the same season since 1953. Georgia also lost five in a row spanning two seasons in 1963-64.
"Losing's not good, but there's a lot of good things that came out as far as the effort and just the attitude and belief," Richt said. "There's a lot of things I could point to as a coach to be proud of, but the bottom line of football is wins and losses and right now we haven't got a win in a while."
This was the last cross-country road game for Georgia in the foreseeable future after new athletic director Greg McGarity was able to cancel a series with Oregon for 2015-16.
The Bulldogs' woes were a topic on ESPN's College Gameday on Saturday morning. Host Chris Fowler labeled Georgia as "September's most disappointing team." Georgia fans showed up in large numbers, making up perhaps a fourth of the crowd, but they left dissapointed.
"It's tough," Green said. "I've never been 1-4 in my life. We're going to stay together and we're going to keep fighting."
Georgia's defense gave up a touchdown on the opponent's first possession for the fourth straight game when Tyler Hansen hit Matt Bahr for a 4-yard touchdown.
Colorado opened a 14-3 lead before Green got his first touch on a 40-yard end-around early in the second quarter.
Then came what may have been his most spectacular catch of his career - a leaping left-handed grab over cornerback Jalil Brown for a 3-yard touchdown.
"That was unbelievable," quarterback Aaron Murray said. "No other receiver in the nation can make that catch." Green wasn't done. Murray hit Green on the run for a 39-yard touchdown with 7:53 left in the second quarter for a 17-14 Georgia lead.
Georgia extended its lead to 24-14 after Murray hit Green for a 50-yard gain early in the second half, but he left the game with cramps. Murray then found Marlon Brown for his first career touchdown in the back of the end zone for 8 yards.
Colorado trimmed the Georgia lead to 24-22 after Rodney Stewart took a pitch 65 yards - his career long - to set up a 2-yard touchdown run by Hansen.
Colorado scored on a two-point conversion pass from Cody Hawkins, the son of coach Dan Hawkins, to Ryan Deehan to cut the lead to two with 7:46 left in the third quarter.
Georgia went three-and-out and Colorado took advantage of a couple of plays involving Vance Cuff.
First, Hansen hit Will Jefferson deep, beating Cuff for a 46-yard gain.
Then, after Cuff ran into kicker Aric Goodman on a field goal, Stewart took a pitch for a 11-yard touchdown run for a 29-24 lead.
Georgia got the ball on first-and-goal at the 4. After a 2-yard Shuan Chapas run, Murray was off-target to Green and a pass to Orson Charles in the end zone was broken up.
Blair Walsh's 20-yard field goal pulled Georgia to 29-27.
Colorado couldn't extend its lead when Goodman missed a 52-yard field goal try with 3:37 left, but Georgia couldn't take advantage.
King rushed for 100 yards on 12 carries - his second 100-yard game of his career - but the fumble will linger.
"I thought it was a shoo-in, that's how comfortable I was," Dobbs said of thinking Georgia was headed for a win. "I put my helmet down, I was ready to run on the field and celebrate, but it didn't happen that way."
Not this season for Georgia.