Football's rulemakers changed the sport forever on Thursday when they approved the use of goal-line technology.
The International FA Board voted in favour of introducing the technology, with two systems being given the go-ahead for use: Hawk-Eye and GoalRef.
Many figures in the game have been crying out for the implementation of a goal-line system, with Ukraine's disallowed goal against England at Euro 2012 prompting FIFA president Sepp Blatter to tweet that goal-line technology was "a necessity". That was just the latest in a long list of outrages that stretches back for years.
The Premier League will not have time to implement the new technology in time for the start of the season, but chief executive Richard Scudamore has not ruled out introducing it at the halfway point of the season this winter.
That means that the Club World Cup in Japan at the end of the year will be the first major competition to use one of the systems.
But what about the two systems that have won approval for use? The British-developed Hawk-Eye will already be well-known to fans of cricket and tennis, while the Danish-German GoalRef system was developed by former international referee Peter Mikelsen.
Both are very different, with their own pros and cons. Here's how they work:
How it works: Six super-high-speed cameras shooting at 500 frames per second (that's 20 times faster than a normal camera) track every movement of the ball as it flies across the pitch.
The images from the different cameras are collected and compared by a computer, which uses the lines painted on the pitch as a static point of reference to help triangulate the precise location of the ball. As seen in England's recent friendly against Belgium (at which the system was tested) the goal netting has to be black and three small black dots are placed on the inside of the goalposts to help the cameras' accuracy.
If the ball crosses the line, an encrypted radio signal is transmitted to a watch worn by the referee which notifies him that a goal has been scored.
Pros: The whole process takes less than a second, and is accurate to within 3.6 millimetres - that's just around an eighth of an inch. The cameras are able to provide a visual display of the ball's path that has already proven an exciting extra element - if one that is often disputed - in both cricket and tennis.
Black goal netting and the black dots that help Hawk-Eye camerasThe ball-tracking isn't limited to use on the goal-line, either - the system would also be a great fit for TV by showing the path of thunderbolt free-kicks and volleys, for example. No wonder it's the system favoured by the Premier League.
Cons: At least 25 per cent of the ball must be visible for the system to work. That means that if the ball went over the line in a melee of bodies after a goalmouth scramble, the system would probably not be able to make a call.
There's also the need to install the high-speed cameras and the black netting, which makes the system both relatively expensive and realistic only at stadiums.
How it works: Electro-magnetic antennas are placed around the goalposts and crossbar to create a sort of invisible curtain of a low-power magnetic field. The ball has electronic probes fitted in between the inflatable inner and the leather outer lining, meaning that the system knows as soon as it crosses the line. As with Hawk-Eye, a signal is then sent to the referee's watch, notifying a goal.
Pros: Because it's a simple magnetic detection system that does not rely on any image processing, GoalRef is almost instantaneous with notification taking less than a tenth of a second.
GoalRef's sensors can be implanted in just about any ball - something which will keep ball sponsors happy. A very similar system named Cairos was an early front-runner for approval as a goal-line technology, but that system fell by the wayside due to the need to hold a microship in the dead centre of expensive and specially-manufactured balls made by system co-creators Adidas.
In fact the whole system is relatively cheap and simple to manufacture compared to the pricey Hawk-Eye system, so much so that a mass-production version is in the pipeline for use at every level above jumpers-for-goalposts.
Cons: It might be simple, but the lack of bells and whistles mean that it's simply nothing like as sexy as Hawk-Eye for TV viewers with all those replay possibilities. However, FIFA have insisted that any system should only be usable by match officials - though probably only while people get used to it - which might give GoalRef a head start.