One of John Hartson's best-ever Celtic goals was scored against Liverpool at Anfield over 21 years ago. It's easy to forget the Welsh forward missed a costly penalty in the Scottish League Cup final a few days earlier.

Having drawn 1-1 with the Reds at Celtic Park on Thursday, March 13, 2003, Martin O'Neill's men prepared for their European return leg the following week.

Sandwiched between the UEFA Cup encounter, however, was the small matter of the League Cup final against Rangers at Hampden on Sunday, March 16.

Celtic lost the match 2-1, and while John Hartson missed a penalty on the day, the striker also scored a perfectly valid goal that was wrongly flagged offside and would have otherwise restored parity on the scoreboard.

Reflecting on that time in his career as part of Celtic TV's 'My Greatest Game' series, Hartson said: "We'd had a little bit of a disappointment in the League Cup final on the Sunday after we'd played Liverpool [at Celtic Park], and unfortunately I missed a penalty and felt as if I'd let everybody down.

"But I also scored in that final and obviously it was wrongly given offside, it was two or three yards onside. I knew I'd timed my run well to make it 2-2, and ultimately that decision probably cost us the game.

"We'd gone 2-0 down in the final, and that goal which wasn't given – which was a goal, I keep saying it, not that I'm bitter – would have let us go into extra-time with the momentum. There's no doubt about that."

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Fast forward four days, and it was Hartson's beautifully taken long range effort that put Celtic two-up at Anfield and on-course for the next round of the UEFA Cup.

In an instant, the disappointment of the previous weekend was forgotten. Hartson added: "My mother and father were in the crowd with the Celtic fans. As soon as I ran out the tunnel [at Anfield] to warm up, I remember it very well, the fans were singing 'There's only one Jonny Hartson' and they were all on their feet.

"They'd obviously looked at the Sunday, realised that I needed a bit of a lift, and they sang my name all the way through.

"When things like that happen, it means an awful lot to a player, when you know you've got the supporters behind you – even though I'd missed that penalty."