Score detection system Hawk-Eye played a major role in last year's drawn All-Ireland final.
With the sides level and seconds of added time remaining Tipperary were awarded a free 97 metres from the Kilkenny goal and John 'Bubbles' O'Dwyer stepped up to take it.
Many in the crowd believed his attempted shot went over the bar and Tipp fans began celebrating what they took to be the winning score.
But the officials were unsure and called for Hawk-Eye, which flashed up on the big screen in Croke Park and showed the sliotar sailing just wide of the post. The full-time whistle was blown on the draw and Kilkenny went on to win the replay.
Without Hawk-Eye would the umpires have called it wide? By the narrowest of margins and with a sea of blue and gold behind the posts adamant it had gone over the bar?
Fans of sport know thinking about what might have been is a futile exercise, but there is no doubt that that Hawk-Eye intervention was a pivotal moment.
With the system in action once more on September 6 as Kilkenny defend their crown against Galway, could we see another crucial intervention and how will it play out if we do?
When Hawkeye was first introduced, in 2013, this video was released to show how the detection system works using eight high speed cameras. Ball position is triangulated using four cameras covering each end and an automated decision is made within one second.
The most common use is where the umpire is unsure of the correct call. He makes a ‘box’ signal with his hands to indicate to the referee that a request for a Hawk-Eye review is being sought. The ref seeks Hawk-Eye review and the Hawk-Eye replay is shown on the big screen.
A more unusual scenario could occur if an umpire makes an incorrect decision regarding a point or wide. A Review Official watches the system during every match and if an incorrect decision is made, will communicate to the ref that a Hawk-Eye review is necessary.
The referee would then make a ‘box’ signal with his hands to seek Hawk-Eye review. The replay would be shown on the big screen, and it would then be up to the referee to confirm the Hawk-Eye call and make the appropriate decision.
However difficult it was for the Tipperary team and fans to accept the Hawk-Eye decision last September, imagine the uproar if the point had been given by the umpires and then overturned in review.
Some football fans thought that should have happened on Sunday in the drawn football semi-final.
Many viewers felt Bernard Brogan’s point in the 13th minute went wide and couldn't understand why the score detection system wasn’t used.
The umpires on Sunday would be wise to refer any marginal calls. They could find themselves caught up in a storm of epic proportions if the Review Official calls a decision into question.