In the moments after Glenn Murray had plundered the winning goal for Brighton & Hove Albion – against his one-time employers, Crystal Palace – it is fair to say that confusion reigned. The striker, who entered as a late substitute, had strained every sinew to reach Uwe Hünemeier’s header towards the far corner but with which body part did he apply the decisive touch?

The replays appeared to show that the ball flicked in off his thigh yet he came awfully close to touching it with his arm, afterwards, before he turned away in triumph. Thankfully, this slow-burning FA Cup tie featured the debut in English club football of the Video Assistant Referee. So, there could be no controversy, right?

Q&A What is VAR? Show Hide The Video Assistant Referee (VAR) system will be used in competitive English football for the first time on Monday night when Brighton host Crystal Palace in the FA Cup third round. What decisions can it be used for? The referee can use VAR on decisions concerning the awarding of goals, penalty kicks, the issuing of straight red cards and cases of mistaken identity. The referee can request assistance with these decisions or it can be recommended by the video officials, but the referee has the final say. Where has it been used? It has been in use all season in Serie A and the Bundesliga, among 15 leagues worldwide to test the technology. Will it be used at the World Cup this summer? Fifa's president Gianni Infantino is keen. The game's law-making body, the International Football Association Board will make a final ruling in March. Have there been any teething problems? There have been concerns over the delays caused by VAR referrals, with Juventus coach Massimiliano Allegri complaining that the game was "turning into baseball". There was also an embarrassing incident in MLS in September when the decision to send off New England Revolution midfielder Xavier Kouassi using VAR was overturned on appeal. How regularly has it been used? ESPN reported there were 309 incidents reviewed using VAR in Serie A up to 30 October. Of those, 288 backed the referee's initial call. Can players, managers or others call for VAR to be used? Players, managers and non-playing staff risk a booking if they attempt to influence any official to use VAR. Photograph: Marco Bertorello/AFP

What actually happened was a lot of nothing but a lot of wondering about what might have happened. Did Neil Swarbrick, who played the role of the video assistant from a studio in west London, review the incident and radio to Andre Marriner, the on-field referee, to tell him that there was no decision to make?

Basically, yes. That is what Chris Hughton, the Brighton manager, said in his post-match press conference and the conclusion to which Roy Hodgson, his opposite number at Palace, jumped. There had been plenty of hand-wringing among the pundits in the BT Sport TV studio and, essentially, disagreement. In real time, Hodgson had raged on the touchline and, after the game, he admitted that he had directed a few “spiteful” words at the officials.

But, in the end, the decision seemed about right and everyone, not least the referees’ chief, Mike Riley, and the Football Association could breathe a sigh of relief. Perhaps the only thing that could be said for certain was that fans would prefer to see the referee perform some sort of VAR routine, making the outline of a television set and going off to check the monitor. Rather that than him hear a whisper in his earpiece and carry on.

It would emerge that Swarbrick had reviewed 11 decisions during the game and referred none of them to Marriner. His silent hand was a big part of the story. This is all going to take a little getting used to. Welcome to the brave new world.

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It was inevitable that Murray would be a central figure against the club where he previously spent four seasons. It looked as though it would not be Brighton’s night after Bakary Sako had equalised for Palace with a bolt from the blue. Sako’s was a firecracker from distance, which ripped past Tim Krul and, when Brighton subsequently hit the post through the substitute, Sam Baldock, and blew other chances, it was easy to fear they had blown it. Murray had other ideas and his goal set up a fourth round trip to Middlesbrough.

Hodgson was more distraught about the injuries that his team picked up than the result. He lost Jeff Schlupp to a knee injury in the early running and Andros Townsend to an ankle problem at half-time. Both players departed the stadium on crutches and they face anxious waits ahead of scans. As Hodgson pointed out, his squad were already carrying too many injuries. Hughton was equally upset to have lost Izzy Brown to what looked like a serious knee problem.

Hodgson had described this as “one the of big games of the year,” with a nod towards the rivalry that has built between these clubs since the late 1970s. It is the derby that does not fit the standard criteria, with the clubs’ stadia being separated by 45 miles. His players did not seem to realise what was at stake and they were second best throughout the first-half.

Quick guide FA Cup fourth round draw Show Hide Liverpool v West Bromwich Albion

Peterborough United v Leicester City

Huddersfield Town v Birmingham City

Notts County v Swansea City

Yeovil Town v Manchester United

Sheffield Wednesday v Reading

Cardiff City v Manchester City

MK Dons v Coventry City

Millwall v Rochdale

Southampton v Watford

Middlesbrough v Brighton

Wigan v West Ham

Hull City v Nottingham Forest

Newport County v Tottenham Hotspur

Chelsea v Newcastle United

Sheffield United v Preston North End Ties to be played between 26 and 29 January Photograph: Tuttle for FA/REX/Shutterstock/Rex Features

Hughton made eight changes from the team that he sent out against Bournemouth last Monday but they went ahead when Palace sprang an almighty leak at the back. Yohan Cabaye stepped out in an attempt to intercept Ezequiel Schelotto’s low pass-back but he did not get there and, when Dale Stephens collected, he burst into the area and yards of space. The Brighton captain shot low, hard and, seemingly, through Wayne Hennessey in the Palace goal.

It said everything that Hodgson sent his players out early for the second half. They were out so early that they had to wait for about three minutes to see their opponents. The sum total of their efforts before the interval had been a couple of bursts from Sako. But he would turn the tie on its head, picking up a loose ball and ramming it past Krul from 25 yards.

Back came Brighton. Baldock hit the post and blew a glorious one-on-one either side of a miss from the otherwise excellent Beram Kayal. The last word, however, would go to Murray – with the blessing of Swarbrick.