VAR - The big incidents and milestones

Credit: PA

The Video Assistant Referee system came in for fresh criticism after Mainz benefited from a bizarre penalty decision which helped seal a controversial 2-0 victory over fellow Freiburg in the Bundesliga.

Freiburg's players had already disappeared down the tunnel for half-time when referee Guido Winkmann referred a potential penalty to the video assistant referee.

Following a delay of around five minutes, Winkmann recalled the visiting players to give the spot-kick after ruling that Daniel Brosinski's cross had been handled by Marc-Oliver Kempf.

Pablo de Blasis duly converted from 12 yards in the seventh minute of first-half added time to give Mainz the lead amid total confusion at the Opel Arena.

Here, Press Association Sport takes a look at other major incidents using the technology.

Cameroon 0 Chile 2 , Confederations Cup (June 18, 2017)

Eduardo Vargas' first-time finish at the end of the first half was ruled out for offside after a referral. However, it took more than a minute from the ball going into the net to the goal being overturned by the VAR and the game was not restarted before the interval. A replay showed Vargas may have been just a few centimetres offside, leaving the incident open to debate as regulations for VAR use state the original decision can only be changed if it is "clearly wrong". Vargas eventually got a goal in stoppage time at the end of the second half, and this time he benefited from a VAR decision as a linesman's offside flag was overturned after Alexis Sanchez ran through and had a shot blocked, allowing Vargas to follow up and score.

Brighton v Crystal Palace, FA Cup (January 8, 2018)

Palace felt Murray may have handled the ball but VAR remained unused. Credit: PA

This was the first competitive game in England where the VAR technology was made available. The system remained unused but there was a hint of controversy as despite suspicions of handball in Glenn Murray's late winner for Brighton against his former club, it was not called upon. The striker's arm was close to making contact with the ball and television replays were inconclusive, but referee Andre Marriner allowed the goal to stand without requesting the use of VAR, meaning Palace were eliminated.

Leicester 2 Fleetwood 0, FA Cup (January 16, 2018)

Jonathan Moss wanted clarity over Iheanacho's goal and VAR was used to good effect. Credit: PA

Leicester became the first team in English football to score a goal via a VAR decision as they overcame Fleetwood 2-0 in their FA Cup replay. Kelechi Iheanacho scored in each half but it was his strike 13 minutes from time that required intervention. Referee Jonathan Moss asked to check if the striker was offside before finishing off Riyad Mahrez's reverse pass. Replays showed Iheanacho was onside when the ball was played and the goal stood to see Leicester progress to a fourth-round tie away at Peterborough.

Chelsea 1 Norwich 1 (Chelsea win 5-3 on penalties), FA Cup (January 17, 2018)

Graham Scott used VAR to see if Willian had been tripped but stuck with his original decision. Credit: PA

Willian was clearly clipped by Canaries defender Timm Klose in the first half of extra time, although referee Graham Scott may have decided the Chelsea forward was already going to ground. However, despite VAR official Mike Jones watching a number of different camera angle replays, he advised Scott his initial decision did not need to be changed.

Liverpool 2 West Brom 3, FA Cup (January 27, 2018)

Liverpool and West Brom's encounter was full of VAR moments. Credit: PA

Liverpool were dumped out of the FA Cup by West Brom in a match littered with VAR referrals which caused confusion on the pitch and in the stands. Three major incidents in the first half of the Reds' 3-2 defeat required the intervention of technology - including the first time a match referee has used a pitchside television replay. Although it eventually led to the correct decisions being made it took almost four minutes between Mohamed Salah being fouled and Craig Pawson awarding a penalty, leaving supporters and players on all sides angry and frustrated.

Huddersfield v Manchester United, FA Cup (February 17, 2018)

Mata's goal was ruled out after VAR's technology deemed to rule him offside when the naked eye thought otherwise. Credit: PA

Juan Mata had a goal disallowed, having been caught narrowly offside, during Manchester United's 2-0 FA Cup fifth-round victory. Match referee Kevin Friend had awarded a goal until the VAR's lengthy intervention. There was controversy after those viewing on BT Sport were shown images of Mata's positioning amid crooked lines that created further confusion surrounding the decision.

Tottenham v Rochdale, FA Cup replay (February 28, 2018)

VAR was involved in nearly every incident during Spurs' match against Rochdale. Credit: PA

Erik Lamela thought he had fired Tottenham ahead only for VAR Graham Scott to controversially rule it out due to slight tugs on Harrison McGahey's shirt by Fernando Llorente. Lucas Moura was then felled by McGahey in the area, with no penalty the eventual - but far from definitive - decision, before Spurs were awarded a spot-kick when Kieran Trippier was held back by Matt Done. VAR again intervened, this time seemingly deciding that because the foul had continued into the area Tottenham should be awarded a penalty. It was only in keeping with the tone of slapstick when Son Heung-min, having paused during his run-up, had his successful penalty disallowed and was booked for his troubles. Tierney double-checked with VAR, naturally, with more time wasted and players and fans becoming more and more bemused.