LEXINGTON, Kent. - When Kentucky receiver Randall Cobb reached out his hands, hauled in the pass and scored the touchdown that capped the Wildcats’ improbable comeback Saturday, Arkansas linebacker Jerry Franklin’s heart dropped

“I just couldn’t believe he caught it,” Franklin said. “It took away a very good day for the defense. The last couple minutes of the game really, really hurt our team.”

Arkansas had been so stingy for the first 55 minutes of Saturday’s 21-20 loss at Kentucky. The Razorbacks shut out the Wildcats in the first half, forced a struggling offense to commit four turnovers and they made only one mistake: A tackling error that led to a 72-yard touchdown pass.

But all the good was wiped away when Kentucky scored two touchdowns in the final 4:15 to erase a 13-point deficit.

Mike Hartline threw a 32-yard touchdown pass to Cobb to help the Wildcats close to 20-14 with 4:15 left. He tossed the game-winner to Cobb a few minutes later, when the receiver beat linebacker Freddy Burton for a 21-yard score.

Arkansas said neither play should’ve happened.

“They got pass protection and gave (Hartline) time and he stood in there and made good throws,” Arkansas coach Bobby Petrino said. “We didn’t execute in our coverage and we didn’t execute in our pass rush.”

The fourth quarter failure came one week after Arkansas’ big win at Auburn, when the maligned defense gained confidence by limiting the Tigers to 193 yards.

The Razorbacks were heading down a similar path at Kentucky and looked like they had sealed a win when cornerback Ramon Broadway intercepted a Hartline pass with 4:56 remaining. But Arkansas running back De’Anthony Curtis fumbled the ball on the very next play and the ‘Cats offense came alive against the Razorbacks.

The ease of the two scores was astonishing. The Wildcats touchdown drives were a combined four plays for 76 yards. They took a total of 50 seconds.

Kentucky needed 61 plays to gain 299 yards before that.

“It’s obvious that we didn’t execute,” Arkansas defensive coordinator Willy Robinson said. “Put it on me.”

Robinson was pressed about the difference in the defense at the end of the game. Once again, he blamed himself.

“It’s more of an in-house deal that we’ll take care of,” he said. “Again, it’s on me. I called a bad game at the very critical part of the game. By not being a good teacher.”

Defensive tackle Malcolm Sheppard and safety Elton Ford offered another explanation. They said there was some confusion with the signals coming from Arkansas’ sideline.

The Razorbacks have two defensive coaches signaling plays every down. One coach is signaling the correct play. The other is calling a dummy designed to throw off opponents.

Sheppard said some of the Razorbacks were getting the wrong ones. He said the coaches weren’t at fault.

“It was our mistake,” Sheppard said. “We were seeing multiple calls on the sideline and that caused some confusion. But it was nothing negative on the coaches. It was on our behalf. They had already told us.”

But Sheppard said the Razorbacks also hurt themselves by failing to make plays no matter what the signals were.

“We could’ve played better in the fourth quarter,” Sheppard said. “Everybody. Including myself. I could’ve ran a little harder or made a leap to get a tackle.”

Arkansas’ failure to do so led to a stunning loss. And it dented a defense that had made so much progress of late.

“We couldn’t finish,” Robinson said. “One of the questions asked earlier in the week was, ‘ How will we handle success?’ Well, we got our answer. We didn’t finish the game.”