LONDON (Reuters) - Introduced to provide help for under pressure referees, the role of Video Assistant Referees (VAR) still remains unclear after more questions over consistency arose at Wembley on Sunday.
With Southampton trailing Chelsea 1-0 in the FA Cup semi-final, referee Martin Atkinson blew for a foul on Chelsea goalkeeper Willy Caballero moments before he appeared to drop the ball over his goalline.
The VAR was not consulted and the decision to award Chelsea, who went on to win the game 2-0, a free kick stood, much to the annoyance of Southampton manager Mark Hughes.
"We're disappointed with the officials," Hughes said. "It was a match-defining moment. Who knows how the game might have followed from that moment?"
VAR will be used throughout the World Cup in Russia this year after FIFA's rule-making panel voted to write VARs into the laws of football.
"I was sceptical at the beginning but without trying things you can't know what they are worth," FIFA President Gianni Infantino said.
"That's why we carried out trials in those 1,000 matches. There are facts: referees make one important mistake one in every three, with VAR it is every 19."
England coach Gareth Southgate was less optimistic of VAR's success in Russia after Italy were awarded a last-minute penalty in a friendly last month, with German referee Deniz Aytekin changing his decision after being advised by the VAR to watch a replay.
"I'm glad it's not the World Cup just yet," Southgate said. "I think the ruling is 'clear and obvious' and it's not. It's one you can debate all day."
The latest setback centres around why VAR was not consulted at all in a competition that has provided a testing-ground for it this season.
"If ever there was a situation for VAR to play a hand and step in to review that was it," Hughes added.
VAR was not employed in either FA Cup semi-final this weekend which is surprising given that 10 separate decisions were reviewed in the last Cup match at Wembley - Tottenham Hotspur's fifth-round replay against Rochdale.
VAR will not be used in the Premier League next season after clubs voted against it and the system remains very much unproven with the World Cup sure to bring up further issues about its value.
(Reporting by Peter Hall, editing by Ed Osmond)