Former Celtic man John Hartson admitted he got it wrong as he revisited the Calvin Bassey offside decision.
The ex-striker was on punditry duty at the national stadium for the Hoops' Scottish Cup semi-final meeting with Rangers.
With the knife-edge derby in extra-time following goals from Greg Taylor and Scott Arfield, tensions were high when Bassey delivered a low ball that deflected off Carl Starfelt and into the Celtic net.
In the replays Hartson had suggested the Nigerian's hand was ahead of the green and white defence when he received the ball on the overlap.
Hands and arms are not included when weighing up offside calls and he admitted on Go Radio on Tuesday evening: "Was it not his hand or his arm? That doesn’t matter now, I actually called it on television and said his arm and hand was offside.
"But when I got home, I actually looked at the rules - which I should’ve done before the game, not after it - and it’s more so your shoulders.
"Your hand and your arm don't count."
Harton had said on TV: "The thing is whether it’s off or on, his left hand looks a bit offside, but you could also say it’s a nicely weighted ball."
