What went right: CU could not have played much better in the first half. Despite losing starting QB Sefo Liufau to injury, the Buffs were fired up from the start and built a 17-3 lead at one point.
What went wrong: The second half could not have been more disappointing. After taking a 17-6 lead into the break, the Buffs gave up 21 consecutive points to start the second half. A fumble and a blocked field goal helped set up two of those USC touchdowns.
Turning point: After taking an 11-point lead into the second half, CU got the ball to start the third quarter, but couldn't do anything with it and punted. USC responded with a 13-play, 83-yard touchdown drive that seized momentum.
CU player of the game: Cade Apsay. The freshman quarterback came off the bench and helped the Buffs stay in the game all night long. He threw for 128 yards and two touchdowns.
Bottom line: Yet another close Pac-12 loss likely ended CU's bowl hopes. The Buffs are now 4-7 and need to win their last two - both on the road - just to have a long shot at a bowl.
Sefo Liufau told his coach that he was ready to keep playing because, well, that's what Liufau has done all year.
A shoulder sprain early in the season didn't keep the Colorado quarterback from playing. Neither did a wrist injury two weeks ago, or any of the other bumps and bruises he's sustained this season.
On Friday night, however, CU head coach Mike MacIntyre looked his junior quarterback in the eyes and had to tell him no.
"I said, 'You can't go back in,'" MacIntyre said.
Liufau didn't finish the game, and he won't finish the season. The junior suffered a Lisfranc fracture to his left foot during the Buffaloes' 27-24 loss to Southern California on Friday at Folsom Field.
Liufau will be sidelined six-to-eight months, meaning he will miss spring ball, as well.
"It was tough, because he was hot," MacIntyre said of Liufau, who was off to a great start Friday night. "I knew it (Wednesday and Thursday) he was going to have a great day. I felt for him because he's taken a little bit of heat and this was going to kind of be his time."
Unfortunately for the Buffs, time ran out on Liufau, who spent the final three quarters on crutches.
Liufau did not speak with reporters after the game, but Tweeted, "Appreciate all the kind words from everyone. I will be back as soon as I can. #GoBuffs."
Without their leader, the Buffs (4-7, 1-6 Pac-12) nearly pulled off an upset of the heavily favored Trojans (7-3, 5-2), but wound up with a result that has been painfully familiar.
The Buffs fell to 1-15 in Pac-12 games over the past two years, with seven of those losses by a touchdown or less.
"We did well, but it's never well enough," sixth-year senior safety Jered Bell said. "It's very disappointing, because I know we can beat these teams and we believe we can beat these teams."
As they usually do, the Buffs played tough all night. In fact, despite losing Liufau, they didn't crumble.
Liufau went 6-for-8 for 94 yards and was as sharp as he's been all year. He staked the Buffs to a 7-3 lead before the play that ended his season.
USC's Kenny Bigelow Jr. sacked Liufau on the final play of the first quarter. Liufau limped off the field.
"I saw him limping around and thought, 'Oh, he's alright,'" CU senior receiver Nelson Spruce said.
Not this time.
After the quarter switch, Apsay took over and was immediately sacked on his first play, forcing the Buffs the punt.
CU's good fortune appeared to be over, but Bell made sure it wasn't.
Playing in his final game at Folsom Field, Bell picked off a Cody Kessler pass and returned it to the Trojans' 26-yard line.
Five plays later, Apsay, who had thrown just 11 career passes, tossed a 9-yard touchdown pass to Spruce for a 14-3 CU lead.
Apsay then led the Buffs to a field goal, and a 17-3 lead, on his next possession.
"Really, I was just ready," Apsay said. "The second I saw (Liufau) struggling to get up, it wasn't a frightened mood or anything. I was ready. I was confident."
Despite not having Liufau, the Buffs took a stunning 17-6 lead into halftime.
In the second half, though, Kessler threw three touchdown passes. One of them came after a CU fumble and another came one play after the Trojans blocked a field goal attempt.
The Kessler-led 24-0 run gave USC a 27-17 lead early in the fourth quarter.
CU didn't collapse, though.
Midway through the fourth quarter, Spruce had a 45-yard punt return to set up a 1-yard touchdown pass from Apsay to George Frazier.
The CU defense forced a USC punt, giving the offense one last chance. Apsay was off the mark on a deep fourth-down pass, though, and USC ran out the clock.
Afterward, MacIntyre took more than an hour to show up to his postgame press conference. When he finally did, he had pain in his eyes and voice.
"This hurt. That's why I'm late," MacIntyre said. "This hurt. With Sefo's situation and all of that, this hurt. This really hurt. It hurt the guys in there.
"They've destroyed us, to be honest with you, the last two years. We had our opportunities. (The players) feel it, they sense it. When you come that close, it even hurts more."
Contact staff writer Brian Howell at email@example.com or twitter.com/BrianHowell33.
SOUTHERN CAL 27, COLORADO 24Southern Cal 3 3 14 7 — 27 Colorado 7 10 0 7 — 24
USC — FG Wood 22, 10:35. Col — Lindsay 4 run (Gonzalez kick), 5:15.
Col — Spruce 9 pass from Apsay (Gonzalez kick), 9:28. Col — FG Gonzalez 28, 3:14. USC — FG Wood 41, :00.
USC — Pinner 4 pass from Kessler (Wood kick), 5:34. USC — McNamara 2 pass from Kessler (Wood kick), 2:32.
USC — Smith-Schuster 36 pass from Kessler (Wood kick), 13:55. Col — Frazier 1 pass from Apsay (Gonzalez kick), 6:13. A — 37,905.
RUSHING — Southern Cal, J.Davis 14-85, Jones II 19-61,Team 2-(minus 3), Kessler 2-(minus 14). Colorado, Lee 7-32, Carr 7-24,Lindsay 8-24, Powell 4-11, Liufau 2-4, Apsay 8-(minus 36).
PASSING — Southern Cal, Kessler 17-27-1-204. Colorado,Apsay 18-23-0-128, Liufau 6-8-0-94.
RECEIVING — Southern Cal, Smith-Schuster 3-66, Mitchell Jr. 3-59,J.Davis 3-28, Hampton 2-19, Rogers 1-14, Petite 1-9, Pinner 1-4,Jackson 1-3, McNamara 1-2, Jones II 1-0. Colorado, Spruce 7-94,Fields 3-24, Ross 3-7, Carr 2-29, Lee 2-23, S.Irwin 2-21, Frazier 2-10,Lindsay 2-8, MacIntyre 1-6.