The on-loan Manchester City man somehow failed to find the net in Sunday’s William Hill Scottish Cup semi-final against Rangers, missing an open goal from just six yards out.
It was an incredible blunder from the €15 million former Fulham youngster, and let the Gers off the hook at a crucial point in the pulsating Old Firm clash, which the Ibrox men went on to win on penalties following a 2-2 draw.
Mark Warburton’s team were leading 1-0 when the ball dropped for Roberts after a Leigh Griffiths effort had come back off the post, but he blasted into the side-netting when it seemed easier to score.
The 19-year-old said: “I should be scoring that and I know I should be. In any other game I would be putting that away. It just came to me and I hit the side-netting. I was distraught.
“It happens in your career. You have bad moments and that is definitely my worst ever. It will probably be the worst I ever have.
“I wasn’t nervous before the game. I knew what it was going to be like to play against Rangers and knew what I had to do. It just wasn’t good enough from me.
“I will come back from this, though. Right now I’m very disappointed for myself and the team.”
Championship winners Rangers twice took the lead through goals from Kenny Miller and Barrie McKay — only to be pegged back by the top-flight champions-elect as substitutes Erik Sviatchenko and Tom Rogic both netted.
But the Light Blues — who stuck impressively to their passing ethos — got the win their stylish play deserved when Rogic blazed his decisive spot-kick over the bar during the nerve-shredding shoot-out.
“It’s the worst possible way to go out of a semi-final — on penalties at Hampden to your rivals,” Roberts said. “We’re just distraught.
“But we have no complaints. We know it wasn’t good enough.”
Hoops boss Ronny Deila now faces serious questions over his leadership.
Celtic are on course for their fifth straight league title but Deila’s European record is dismal. However, Roberts said the Norwegian’s players deserve a share of the blame.
“The manager has been great for me,” he said. “Do the players have to take responsibility? Yeah definitely. We know it wasn’t good enough. We need to pick our heads up, though, and win the league.”
As for the winners, Miller was delighted with the surprise result.
“It was extra special,” the 36-year-old striker said. “A lot of people outside of Rangers never gave us a chance, but we were completely confident.
“The fact it went to penalties as well made it emotional. You’re standing there watching it with your heart pounding.
“You’re hoping your keeper makes a save, that your guys score. It was hard to watch.
“But we had full belief and I really felt it would be our day.
“We were the dominant side — there’s no getting away from that.”
Foderingham, Tavernier, Kiernan (Zelalem 88), Danny Wilson, Wallace, Ball, Shiels (Law 66), Halliday, Holt, McKay, Miller (Clark 91).
Gordon, Lustig,Boyata (Sviatchenko 25), Mulgrew, Tierney, Brown, Bitton, Roberts, Johansen (Rogic 84), Mackay-Steven (McGregor 71), Griffiths.
Kazim-Richards, Armstrong, Commons, Bailly.
Craig Thomson (Scotland).